Paul B Mahol (12019-10-28): > The new API is more extensible and allows for custom layouts. > More accurate information is exported, eg for decoders that do not > set a channel layout, lavc will not make one up for them. > > Deprecate the old API working with just uint64_t bitmasks. > > Original commit by Anton Khirnov <an...@khirnov.net>. > Expanded and completed by Vittorio Giovara <vittorio.giov...@gmail.com>. > Adapted for FFmpeg by Paul B Mahol <one...@gmail.com>. > > Signed-off-by: Anton Khirnov <an...@khirnov.net> > Signed-off-by: Vittorio Giovara <vittorio.giov...@gmail.com> > Signed-off-by: Paul B Mahol <one...@gmail.com> > --- > libavutil/channel_layout.c | 385 ++++++++++++++++++++++++++++------ > libavutil/channel_layout.h | 411 ++++++++++++++++++++++++++++++++++--- > libavutil/version.h | 3 + > 3 files changed, 709 insertions(+), 90 deletions(-)
Just a few quick remarks on the API itself for now. I did not read the
implementation carefully.
> diff --git a/libavutil/channel_layout.c b/libavutil/channel_layout.c
> index 3bd5ee29b7..9112af32a6 100644
> --- a/libavutil/channel_layout.c
> +++ b/libavutil/channel_layout.c
> @@ -37,75 +37,87 @@ struct channel_name {
> };
>
> static const struct channel_name channel_names[] = {
> - [0] = { "FL", "front left" },
> - [1] = { "FR", "front right" },
> - [2] = { "FC", "front center" },
> - [3] = { "LFE", "low frequency" },
> - [4] = { "BL", "back left" },
> - [5] = { "BR", "back right" },
> - [6] = { "FLC", "front left-of-center" },
> - [7] = { "FRC", "front right-of-center" },
> - [8] = { "BC", "back center" },
> - [9] = { "SL", "side left" },
> - [10] = { "SR", "side right" },
> - [11] = { "TC", "top center" },
> - [12] = { "TFL", "top front left" },
> - [13] = { "TFC", "top front center" },
> - [14] = { "TFR", "top front right" },
> - [15] = { "TBL", "top back left" },
> - [16] = { "TBC", "top back center" },
> - [17] = { "TBR", "top back right" },
> - [29] = { "DL", "downmix left" },
> - [30] = { "DR", "downmix right" },
> - [31] = { "WL", "wide left" },
> - [32] = { "WR", "wide right" },
> - [33] = { "SDL", "surround direct left" },
> - [34] = { "SDR", "surround direct right" },
> - [35] = { "LFE2", "low frequency 2" },
> + [AV_CHAN_FRONT_LEFT ] = { "FL" },
> + [AV_CHAN_FRONT_RIGHT ] = { "FR" },
> + [AV_CHAN_FRONT_CENTER ] = { "FC" },
> + [AV_CHAN_LOW_FREQUENCY ] = { "LFE" },
> + [AV_CHAN_BACK_LEFT ] = { "BL" },
> + [AV_CHAN_BACK_RIGHT ] = { "BR" },
> + [AV_CHAN_FRONT_LEFT_OF_CENTER ] = { "FLC" },
> + [AV_CHAN_FRONT_RIGHT_OF_CENTER ] = { "FRC" },
> + [AV_CHAN_BACK_CENTER ] = { "BC" },
> + [AV_CHAN_SIDE_LEFT ] = { "SL" },
> + [AV_CHAN_SIDE_RIGHT ] = { "SR" },
> + [AV_CHAN_TOP_CENTER ] = { "TC" },
> + [AV_CHAN_TOP_FRONT_LEFT ] = { "TFL" },
> + [AV_CHAN_TOP_FRONT_CENTER ] = { "TFC" },
> + [AV_CHAN_TOP_FRONT_RIGHT ] = { "TFR" },
> + [AV_CHAN_TOP_BACK_LEFT ] = { "TBL" },
> + [AV_CHAN_TOP_BACK_CENTER ] = { "TBC" },
> + [AV_CHAN_TOP_BACK_RIGHT ] = { "TBR" },
> + [AV_CHAN_STEREO_LEFT ] = { "DL" },
> + [AV_CHAN_STEREO_RIGHT ] = { "DR" },
> + [AV_CHAN_WIDE_LEFT ] = { "WL" },
> + [AV_CHAN_WIDE_RIGHT ] = { "WR" },
> + [AV_CHAN_SURROUND_DIRECT_LEFT ] = { "SDL" },
> + [AV_CHAN_SURROUND_DIRECT_RIGHT ] = { "SDR" },
> + [AV_CHAN_LOW_FREQUENCY_2 ] = { "LFE2" },
> + [AV_CHAN_SILENCE ] = { "PAD" },
> };
>
> -static const char *get_channel_name(int channel_id)
> +const char *av_channel_name(enum AVChannel channel_id)
> {
> if (channel_id < 0 || channel_id >= FF_ARRAY_ELEMS(channel_names))
> return NULL;
> return channel_names[channel_id].name;
> }
>
> +int av_channel_from_string(const char *str)
> +{
> + for (int i = 0; i < FF_ARRAY_ELEMS(channel_names); i++) {
> + if (channel_names[i].name && !strcmp(str, channel_names[i].name)) {
> + return i;
> + }
> + }
> + return AVERROR(EINVAL);
> +}
> +
> static const struct {
> const char *name;
> - int nb_channels;
> - uint64_t layout;
> + AVChannelLayout layout;
> } channel_layout_map[] = {
> - { "mono", 1, AV_CH_LAYOUT_MONO },
> - { "stereo", 2, AV_CH_LAYOUT_STEREO },
> - { "2.1", 3, AV_CH_LAYOUT_2POINT1 },
> - { "3.0", 3, AV_CH_LAYOUT_SURROUND },
> - { "3.0(back)", 3, AV_CH_LAYOUT_2_1 },
> - { "4.0", 4, AV_CH_LAYOUT_4POINT0 },
> - { "quad", 4, AV_CH_LAYOUT_QUAD },
> - { "quad(side)", 4, AV_CH_LAYOUT_2_2 },
> - { "3.1", 4, AV_CH_LAYOUT_3POINT1 },
> - { "5.0", 5, AV_CH_LAYOUT_5POINT0_BACK },
> - { "5.0(side)", 5, AV_CH_LAYOUT_5POINT0 },
> - { "4.1", 5, AV_CH_LAYOUT_4POINT1 },
> - { "5.1", 6, AV_CH_LAYOUT_5POINT1_BACK },
> - { "5.1(side)", 6, AV_CH_LAYOUT_5POINT1 },
> - { "6.0", 6, AV_CH_LAYOUT_6POINT0 },
> - { "6.0(front)", 6, AV_CH_LAYOUT_6POINT0_FRONT },
> - { "hexagonal", 6, AV_CH_LAYOUT_HEXAGONAL },
> - { "6.1", 7, AV_CH_LAYOUT_6POINT1 },
> - { "6.1(back)", 7, AV_CH_LAYOUT_6POINT1_BACK },
> - { "6.1(front)", 7, AV_CH_LAYOUT_6POINT1_FRONT },
> - { "7.0", 7, AV_CH_LAYOUT_7POINT0 },
> - { "7.0(front)", 7, AV_CH_LAYOUT_7POINT0_FRONT },
> - { "7.1", 8, AV_CH_LAYOUT_7POINT1 },
> - { "7.1(wide)", 8, AV_CH_LAYOUT_7POINT1_WIDE_BACK },
> - { "7.1(wide-side)", 8, AV_CH_LAYOUT_7POINT1_WIDE },
> - { "octagonal", 8, AV_CH_LAYOUT_OCTAGONAL },
> - { "hexadecagonal", 16, AV_CH_LAYOUT_HEXADECAGONAL },
> - { "downmix", 2, AV_CH_LAYOUT_STEREO_DOWNMIX, },
> + { "mono", AV_CHANNEL_LAYOUT_MONO },
> + { "stereo", AV_CHANNEL_LAYOUT_STEREO },
> + { "2.1", AV_CHANNEL_LAYOUT_2POINT1 },
> + { "3.0", AV_CHANNEL_LAYOUT_SURROUND },
> + { "3.0(back)", AV_CHANNEL_LAYOUT_2_1 },
> + { "4.0", AV_CHANNEL_LAYOUT_4POINT0 },
> + { "quad", AV_CHANNEL_LAYOUT_QUAD },
> + { "quad(side)", AV_CHANNEL_LAYOUT_2_2 },
> + { "3.1", AV_CHANNEL_LAYOUT_3POINT1 },
> + { "5.0", AV_CHANNEL_LAYOUT_5POINT0_BACK },
> + { "5.0(side)", AV_CHANNEL_LAYOUT_5POINT0 },
> + { "4.1", AV_CHANNEL_LAYOUT_4POINT1 },
> + { "5.1", AV_CHANNEL_LAYOUT_5POINT1_BACK },
> + { "5.1(side)", AV_CHANNEL_LAYOUT_5POINT1 },
> + { "6.0", AV_CHANNEL_LAYOUT_6POINT0 },
> + { "6.0(front)", AV_CHANNEL_LAYOUT_6POINT0_FRONT },
> + { "hexagonal", AV_CHANNEL_LAYOUT_HEXAGONAL },
> + { "6.1", AV_CHANNEL_LAYOUT_6POINT1 },
> + { "6.1(back)", AV_CHANNEL_LAYOUT_6POINT1_BACK },
> + { "6.1(front)", AV_CHANNEL_LAYOUT_6POINT1_FRONT },
> + { "7.0", AV_CHANNEL_LAYOUT_7POINT0 },
> + { "7.0(front)", AV_CHANNEL_LAYOUT_7POINT0_FRONT },
> + { "7.1", AV_CHANNEL_LAYOUT_7POINT1 },
> + { "7.1(wide)", AV_CHANNEL_LAYOUT_7POINT1_WIDE },
> + { "7.1(wide-back)", AV_CHANNEL_LAYOUT_7POINT1_WIDE_BACK },
> + { "octagonal", AV_CHANNEL_LAYOUT_OCTAGONAL },
> + { "hexadecagonal", AV_CHANNEL_LAYOUT_HEXADECAGONAL },
> + { "downmix", AV_CHANNEL_LAYOUT_STEREO_DOWNMIX, },
> };
>
> +#if FF_API_OLD_CHANNEL_LAYOUT
> +FF_DISABLE_DEPRECATION_WARNINGS
> static uint64_t get_channel_layout_single(const char *name, int name_len)
> {
> int i;
> @@ -115,7 +127,7 @@ static uint64_t get_channel_layout_single(const char
> *name, int name_len)
> for (i = 0; i < FF_ARRAY_ELEMS(channel_layout_map); i++) {
> if (strlen(channel_layout_map[i].name) == name_len &&
> !memcmp(channel_layout_map[i].name, name, name_len))
> - return channel_layout_map[i].layout;
> + return channel_layout_map[i].layout.u.mask;
> }
> for (i = 0; i < FF_ARRAY_ELEMS(channel_names); i++)
> if (channel_names[i].name &&
> @@ -183,8 +195,8 @@ void av_bprint_channel_layout(struct AVBPrint *bp,
> nb_channels = av_get_channel_layout_nb_channels(channel_layout);
>
> for (i = 0; i < FF_ARRAY_ELEMS(channel_layout_map); i++)
> - if (nb_channels == channel_layout_map[i].nb_channels &&
> - channel_layout == channel_layout_map[i].layout) {
> + if (nb_channels == channel_layout_map[i].layout.nb_channels &&
> + channel_layout == channel_layout_map[i].layout.u.mask) {
> av_bprintf(bp, "%s", channel_layout_map[i].name);
> return;
> }
> @@ -195,7 +207,7 @@ void av_bprint_channel_layout(struct AVBPrint *bp,
> av_bprintf(bp, " (");
> for (i = 0, ch = 0; i < 64; i++) {
> if ((channel_layout & (UINT64_C(1) << i))) {
> - const char *name = get_channel_name(i);
> + const char *name = av_channel_name(i);
> if (name) {
> if (ch > 0)
> av_bprintf(bp, "+");
> @@ -225,8 +237,8 @@ int av_get_channel_layout_nb_channels(uint64_t
> channel_layout)
> int64_t av_get_default_channel_layout(int nb_channels) {
> int i;
> for (i = 0; i < FF_ARRAY_ELEMS(channel_layout_map); i++)
> - if (nb_channels == channel_layout_map[i].nb_channels)
> - return channel_layout_map[i].layout;
> + if (nb_channels == channel_layout_map[i].layout.nb_channels)
> + return channel_layout_map[i].layout.u.mask;
> return 0;
> }
>
> @@ -247,7 +259,7 @@ const char *av_get_channel_name(uint64_t channel)
> return NULL;
> for (i = 0; i < 64; i++)
> if ((1ULL<<i) & channel)
> - return get_channel_name(i);
> + return av_channel_name(i);
> return NULL;
> }
>
> @@ -281,7 +293,252 @@ int av_get_standard_channel_layout(unsigned index,
> uint64_t *layout,
> {
> if (index >= FF_ARRAY_ELEMS(channel_layout_map))
> return AVERROR_EOF;
> - if (layout) *layout = channel_layout_map[index].layout;
> + if (layout) *layout = channel_layout_map[index].layout.u.mask;
> if (name) *name = channel_layout_map[index].name;
> return 0;
> }
> +
> +FF_ENABLE_DEPRECATION_WARNINGS
> +#endif
> +
> +void av_channel_layout_from_mask(AVChannelLayout *channel_layout,
> + uint64_t mask)
> +{
> + channel_layout->order = AV_CHANNEL_ORDER_NATIVE;
> + channel_layout->nb_channels = av_popcount64(mask);
> + channel_layout->u.mask = mask;
> +}
> +
> +int av_channel_layout_from_string(AVChannelLayout *channel_layout,
> + const char *str)
> +{
> + int i, channels;
> + const char *dup = str;
> + uint64_t mask = 0;
> +
> + /* channel layout names */
> + for (i = 0; i < FF_ARRAY_ELEMS(channel_layout_map); i++) {
> + if (channel_layout_map[i].name && !strcmp(str,
> channel_layout_map[i].name)) {
> + *channel_layout = channel_layout_map[i].layout;
> + return 0;
> + }
> + }
> +
> + /* channel names */
> + while (*dup) {
> + char *chname = av_get_token(&dup, "+");
> + if (!chname)
> + return AVERROR(ENOMEM);
> + if (*dup)
> + dup++; // skip separator
> + for (i = 0; i < FF_ARRAY_ELEMS(channel_names); i++) {
> + if (channel_names[i].name && !strcmp(chname,
> channel_names[i].name)) {
> + mask |= 1ULL << i;
> + }
> + }
> + av_free(chname);
> + }
> + if (mask) {
> + av_channel_layout_from_mask(channel_layout, mask);
> + return 0;
> + }
> +
> + /* channel layout mask */
> + if (!strncmp(str, "0x", 2) && sscanf(str, "%"PRIx64, &mask) == 1) {
> + av_channel_layout_from_mask(channel_layout, mask);
> + return 0;
> + }
> +
> + /* number of channels */
> + if (sscanf(str, "%d", &channels) == 1) {
> + av_channel_layout_default(channel_layout, channels);
> + return 0;
> + }
> +
> + /* number of unordered channels */
> + if (sscanf(str, "%d channels", &channel_layout->nb_channels) == 1) {
> + channel_layout->order = AV_CHANNEL_ORDER_UNSPEC;
> + return 0;
> + }
> +
> + return AVERROR_INVALIDDATA;
> +}
> +
> +void av_channel_layout_uninit(AVChannelLayout *channel_layout)
> +{
> + if (channel_layout->order == AV_CHANNEL_ORDER_CUSTOM)
> + av_freep(&channel_layout->u.map);
> + memset(channel_layout, 0, sizeof(*channel_layout));
> +}
> +
> +int av_channel_layout_copy(AVChannelLayout *dst, const AVChannelLayout *src)
> +{
> + av_channel_layout_uninit(dst);
> + *dst = *src;
> + if (src->order == AV_CHANNEL_ORDER_CUSTOM) {
> + dst->u.map = av_malloc(src->nb_channels * sizeof(*dst->u.map));
> + if (!dst->u.map)
> + return AVERROR(ENOMEM);
> + memcpy(dst->u.map, src->u.map, src->nb_channels *
> sizeof(*src->u.map));
> + }
> + return 0;
> +}
> +
> +char *av_channel_layout_describe(const AVChannelLayout *channel_layout)
> +{
> + int i;
> +
> + switch (channel_layout->order) {
> + case AV_CHANNEL_ORDER_NATIVE:
> + for (i = 0; channel_layout_map[i].name; i++)
> + if (channel_layout->u.mask ==
> channel_layout_map[i].layout.u.mask)
> + return av_strdup(channel_layout_map[i].name);
> + // fall-through
> + case AV_CHANNEL_ORDER_CUSTOM: {
> + // max 4 bytes for channel name + a separator
> + int size = 5 * channel_layout->nb_channels + 1;
> + char *ret;
> +
> + ret = av_mallocz(size);
> + if (!ret)
> + return NULL;
> +
> + for (i = 0; i < channel_layout->nb_channels; i++) {
> + enum AVChannel ch =
> av_channel_layout_get_channel(channel_layout, i);
> + const char *ch_name = av_channel_name(ch);
> +
> + if (i)
> + av_strlcat(ret, "+", size);
> + av_strlcat(ret, ch_name, size);
> + }
> + return ret;
> + }
> + case AV_CHANNEL_ORDER_UNSPEC: {
> + char buf[64];
> + snprintf(buf, sizeof(buf), "%d channels",
> channel_layout->nb_channels);
> + return av_strdup(buf);
> + }
> + default:
> + return NULL;
> + }
> +}
> +
> +int av_channel_layout_get_channel(const AVChannelLayout *channel_layout, int
> idx)
> +{
> + int i;
> +
> + if (idx < 0 || idx >= channel_layout->nb_channels)
> + return AVERROR(EINVAL);
> +
> + switch (channel_layout->order) {
> + case AV_CHANNEL_ORDER_CUSTOM:
> + return channel_layout->u.map[idx];
> + case AV_CHANNEL_ORDER_NATIVE:
> + for (i = 0; i < 64; i++) {
> + if ((1ULL << i) & channel_layout->u.mask && !idx--)
> + return i;
> + }
> + default:
> + return AVERROR(EINVAL);
> + }
> +}
> +
> +int av_channel_layout_channel_index(const AVChannelLayout *channel_layout,
> + enum AVChannel channel)
> +{
> + int i;
> +
> + switch (channel_layout->order) {
> + case AV_CHANNEL_ORDER_CUSTOM:
> + for (i = 0; i < channel_layout->nb_channels; i++)
> + if (channel_layout->u.map[i] == channel)
> + return i;
> + return AVERROR(EINVAL);
> + case AV_CHANNEL_ORDER_NATIVE: {
> + uint64_t mask = channel_layout->u.mask;
> + if (!(mask & (1ULL << channel)))
> + return AVERROR(EINVAL);
> + mask &= (1ULL << channel) - 1;
> + return av_popcount64(mask);
> + }
> + default:
> + return AVERROR(EINVAL);
> + }
> +}
> +
> +int av_channel_layout_check(const AVChannelLayout *channel_layout)
> +{
> + if (!channel_layout || channel_layout->nb_channels <= 0)
> + return 0;
> +
> + switch (channel_layout->order) {
> + case AV_CHANNEL_ORDER_NATIVE:
> + return av_popcount64(channel_layout->u.mask) ==
> channel_layout->nb_channels;
> + case AV_CHANNEL_ORDER_CUSTOM:
> + return !!channel_layout->u.map;
> + case AV_CHANNEL_ORDER_UNSPEC:
> + return 1;
> + default:
> + return 0;
> + }
> +}
> +
> +int av_channel_layout_compare(const AVChannelLayout *chl, const
> AVChannelLayout *chl1)
> +{
> + /* different channel counts -> not equal */
> + if (chl->nb_channels != chl1->nb_channels && chl->order == chl1->order)
> + return (chl->nb_channels - chl1->nb_channels > 0) -
> (chl1->nb_channels - chl->nb_channels > 0);
> +
> + /* if only one is unspecified -> not equal */
> + if ((chl->order == AV_CHANNEL_ORDER_UNSPEC) !=
> + (chl1->order == AV_CHANNEL_ORDER_UNSPEC))
> + return -2;
> + /* both are unspecified -> equal */
> + else if (chl->order == AV_CHANNEL_ORDER_UNSPEC)
> + return 0;
> +
> + /* can compare masks directly */
> + if (chl->order != AV_CHANNEL_ORDER_CUSTOM &&
> + chl->order == chl1->order)
> + return chl->u.mask == chl1->u.mask ? 0 : -2;
> +
> + /* compare channel by channel */
> + for (int i = 0; i < chl->nb_channels; i++)
> + if (av_channel_layout_get_channel(chl, i) !=
> + av_channel_layout_get_channel(chl1, i))
> + return -2;
> + return 0;
> +}
> +
> +void av_channel_layout_default(AVChannelLayout *ch_layout, int nb_channels)
> +{
> + switch (nb_channels) {
> + case 1: *ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO; break;
> + case 2: *ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_STEREO; break;
> + case 3: *ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_SURROUND; break;
> + case 4: *ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_QUAD; break;
> + case 5: *ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_5POINT0; break;
> + case 6: *ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_5POINT1; break;
> + case 7: *ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_6POINT1; break;
> + case 8: *ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_7POINT1; break;
> + default:
> + ch_layout->order = AV_CHANNEL_ORDER_UNSPEC;
> + ch_layout->nb_channels = nb_channels;
> + }
> +}
> +
> +uint64_t av_channel_layout_subset(const AVChannelLayout *channel_layout,
> + uint64_t mask)
> +{
> + uint64_t ret = 0;
> + int i;
> +
> + if (channel_layout->order == AV_CHANNEL_ORDER_NATIVE)
> + return channel_layout->u.mask & mask;
> +
> + for (i = 0; i < 64; i++)
> + if (mask & (1ULL << i) &&
> av_channel_layout_channel_index(channel_layout, i) >= 0)
> + ret |= (1ULL << i);
> +
> + return ret;
> +}
> diff --git a/libavutil/channel_layout.h b/libavutil/channel_layout.h
> index 50bb8f03c5..a4d76dc4f0 100644
> --- a/libavutil/channel_layout.h
> +++ b/libavutil/channel_layout.h
> @@ -24,6 +24,9 @@
>
> #include <stdint.h>
>
> +#include "version.h"
> +#include "attributes.h"
> +
> /**
> * @file
> * audio channel layout utility functions
> @@ -34,6 +37,60 @@
> * @{
> */
>
> +enum AVChannel {
> + AV_CHAN_FRONT_LEFT,
> + AV_CHAN_FRONT_RIGHT,
> + AV_CHAN_FRONT_CENTER,
> + AV_CHAN_LOW_FREQUENCY,
> + AV_CHAN_BACK_LEFT,
> + AV_CHAN_BACK_RIGHT,
> + AV_CHAN_FRONT_LEFT_OF_CENTER,
> + AV_CHAN_FRONT_RIGHT_OF_CENTER,
> + AV_CHAN_BACK_CENTER,
> + AV_CHAN_SIDE_LEFT,
> + AV_CHAN_SIDE_RIGHT,
> + AV_CHAN_TOP_CENTER,
> + AV_CHAN_TOP_FRONT_LEFT,
> + AV_CHAN_TOP_FRONT_CENTER,
> + AV_CHAN_TOP_FRONT_RIGHT,
> + AV_CHAN_TOP_BACK_LEFT,
> + AV_CHAN_TOP_BACK_CENTER,
> + AV_CHAN_TOP_BACK_RIGHT,
> + /** Stereo downmix. */
> + AV_CHAN_STEREO_LEFT = 29,
> + /** See above. */
> + AV_CHAN_STEREO_RIGHT,
> + AV_CHAN_WIDE_LEFT,
> + AV_CHAN_WIDE_RIGHT,
> + AV_CHAN_SURROUND_DIRECT_LEFT,
> + AV_CHAN_SURROUND_DIRECT_RIGHT,
> + AV_CHAN_LOW_FREQUENCY_2,
> +
> + /** Channel is empty can be safely skipped. */
> + AV_CHAN_SILENCE = 64,
> +};
> +
> +enum AVChannelOrder {
> + /**
> + * The native channel order, i.e. the channels are in the same order in
> + * which they are defined in the AVChannel enum. This supports up to 63
> + * different channels.
> + */
> + AV_CHANNEL_ORDER_NATIVE,
> + /**
> + * The channel order does not correspond to any other predefined order
> and
> + * is stored as an explicit map. For example, this could be used to
> support
> + * layouts with 64 or more channels, or with channels that could be
> skipped.
"or with channels that could be skipped"? What does that mean. If a
channel is skipped, it is not present, that can be expressed in the
mask. Is this a mistake for "duplicated"?
> + */
> + AV_CHANNEL_ORDER_CUSTOM,
> + /**
> + * Only the channel count is specified, without any further information
> + * about the channel order.
> + */
> + AV_CHANNEL_ORDER_UNSPEC,
> +};
> +
> +
> /**
> * @defgroup channel_masks Audio channel masks
> *
> @@ -46,36 +103,41 @@
> *
> * @{
> */
> -#define AV_CH_FRONT_LEFT 0x00000001
> -#define AV_CH_FRONT_RIGHT 0x00000002
> -#define AV_CH_FRONT_CENTER 0x00000004
> -#define AV_CH_LOW_FREQUENCY 0x00000008
> -#define AV_CH_BACK_LEFT 0x00000010
> -#define AV_CH_BACK_RIGHT 0x00000020
> -#define AV_CH_FRONT_LEFT_OF_CENTER 0x00000040
> -#define AV_CH_FRONT_RIGHT_OF_CENTER 0x00000080
> -#define AV_CH_BACK_CENTER 0x00000100
> -#define AV_CH_SIDE_LEFT 0x00000200
> -#define AV_CH_SIDE_RIGHT 0x00000400
> -#define AV_CH_TOP_CENTER 0x00000800
> -#define AV_CH_TOP_FRONT_LEFT 0x00001000
> -#define AV_CH_TOP_FRONT_CENTER 0x00002000
> -#define AV_CH_TOP_FRONT_RIGHT 0x00004000
> -#define AV_CH_TOP_BACK_LEFT 0x00008000
> -#define AV_CH_TOP_BACK_CENTER 0x00010000
> -#define AV_CH_TOP_BACK_RIGHT 0x00020000
> -#define AV_CH_STEREO_LEFT 0x20000000 ///< Stereo downmix.
> -#define AV_CH_STEREO_RIGHT 0x40000000 ///< See AV_CH_STEREO_LEFT.
> -#define AV_CH_WIDE_LEFT 0x0000000080000000ULL
> -#define AV_CH_WIDE_RIGHT 0x0000000100000000ULL
> -#define AV_CH_SURROUND_DIRECT_LEFT 0x0000000200000000ULL
> -#define AV_CH_SURROUND_DIRECT_RIGHT 0x0000000400000000ULL
> -#define AV_CH_LOW_FREQUENCY_2 0x0000000800000000ULL
> +#define AV_CH_FRONT_LEFT (1ULL << AV_CHAN_FRONT_LEFT )
> +#define AV_CH_FRONT_RIGHT (1ULL << AV_CHAN_FRONT_RIGHT )
> +#define AV_CH_FRONT_CENTER (1ULL << AV_CHAN_FRONT_CENTER )
> +#define AV_CH_LOW_FREQUENCY (1ULL << AV_CHAN_LOW_FREQUENCY )
> +#define AV_CH_BACK_LEFT (1ULL << AV_CHAN_BACK_LEFT )
> +#define AV_CH_BACK_RIGHT (1ULL << AV_CHAN_BACK_RIGHT )
> +#define AV_CH_FRONT_LEFT_OF_CENTER (1ULL << AV_CHAN_FRONT_LEFT_OF_CENTER )
> +#define AV_CH_FRONT_RIGHT_OF_CENTER (1ULL << AV_CHAN_FRONT_RIGHT_OF_CENTER)
> +#define AV_CH_BACK_CENTER (1ULL << AV_CHAN_BACK_CENTER )
> +#define AV_CH_SIDE_LEFT (1ULL << AV_CHAN_SIDE_LEFT )
> +#define AV_CH_SIDE_RIGHT (1ULL << AV_CHAN_SIDE_RIGHT )
> +#define AV_CH_TOP_CENTER (1ULL << AV_CHAN_TOP_CENTER )
> +#define AV_CH_TOP_FRONT_LEFT (1ULL << AV_CHAN_TOP_FRONT_LEFT )
> +#define AV_CH_TOP_FRONT_CENTER (1ULL << AV_CHAN_TOP_FRONT_CENTER )
> +#define AV_CH_TOP_FRONT_RIGHT (1ULL << AV_CHAN_TOP_FRONT_RIGHT )
> +#define AV_CH_TOP_BACK_LEFT (1ULL << AV_CHAN_TOP_BACK_LEFT )
> +#define AV_CH_TOP_BACK_CENTER (1ULL << AV_CHAN_TOP_BACK_CENTER )
> +#define AV_CH_TOP_BACK_RIGHT (1ULL << AV_CHAN_TOP_BACK_RIGHT )
> +#define AV_CH_STEREO_LEFT (1ULL << AV_CHAN_STEREO_LEFT )
> +#define AV_CH_STEREO_RIGHT (1ULL << AV_CHAN_STEREO_RIGHT )
> +#define AV_CH_WIDE_LEFT (1ULL << AV_CHAN_WIDE_LEFT )
> +#define AV_CH_WIDE_RIGHT (1ULL << AV_CHAN_WIDE_RIGHT )
> +#define AV_CH_SURROUND_DIRECT_LEFT (1ULL << AV_CHAN_SURROUND_DIRECT_LEFT )
> +#define AV_CH_SURROUND_DIRECT_RIGHT (1ULL << AV_CHAN_SURROUND_DIRECT_RIGHT)
> +#define AV_CH_LOW_FREQUENCY_2 (1ULL << AV_CHAN_LOW_FREQUENCY_2 )
>
> +#if FF_API_OLD_CHANNEL_LAYOUT
> /** Channel mask value used for AVCodecContext.request_channel_layout
> to indicate that the user requests the channel order of the decoder
> output
> - to be the native codec channel order. */
> + to be the native codec channel order.
> + @deprecated channel order is now indicated in a special field in
> + AVChannelLayout
> + */
> #define AV_CH_LAYOUT_NATIVE 0x8000000000000000ULL
> +#endif
>
> /**
> * @}
> @@ -122,6 +184,135 @@ enum AVMatrixEncoding {
> AV_MATRIX_ENCODING_NB
> };
>
> +/**
> + * An AVChannelLayout holds information about the channel layout of audio
> data.
> + *
> + * A channel layout here is defined as a set of channels ordered in a
> specific
> + * way (unless the channel order is AV_CHANNEL_ORDER_UNSPEC, in which case an
> + * AVChannelLayout carries only the channel count).
> + *
> + * Unlike most structures in Libav, sizeof(AVChannelLayout) is a part of the
> + * public ABI and may be used by the caller. E.g. it may be allocated on
> stack.
> + * In particular, this structure can be initialized as follows:
> + * - default initialization with {0} or by setting all used fields correctly
> + * - with predefined layout as initializer (AV_CHANNEL_LAYOUT_STEREO, etc.)
> + * - with a constructor function such as av_channel_layout_default()
> + * On that note, this also applies:
> + * - copy via assigning is forbidden, av_channel_layout_copy() must be used
> + * instead (and its return value should be checked)
> + * - if order is AV_CHANNEL_ORDER_CUSTOM, then it must be uninitialized with
> + * av_channel_layout_uninit().
> + *
> + * No new fields may be added to it without a major version bump, except for
> + * new elements of the union fitting in sizeof(uint64_t).
This is a significant difference from the other APIs, and we need to be
really sure we can live with it.
I am rather for this version, but I am afraid we will find cases that
need extending the structure. After all, the trial by fire for an API is
to be used, this one has not yet had it.
I suggest we explicitly declare this API unstable for a few months,
during which we consider acceptable to add fields.
> + *
> + * An AVChannelLayout can be constructed using the convenience function
> + * av_channel_layout_from_mask() / av_channel_layout_from_string(), or it
> can be
> + * built manually by the caller.
> + */
> +typedef struct AVChannelLayout {
> + /**
> + * Channel order used in this layout.
> + * This is a mandatory field, will default to AV_CHANNEL_ORDER_NATIVE.
> + */
> + enum AVChannelOrder order;
> +
> + /**
> + * Number of channels in this layout. Mandatory field.
> + */
> + int nb_channels;
unsigned.
> +
> + /**
> + * Details about which channels are present in this layout.
> + * For AV_CHANNEL_ORDER_UNSPEC, this field is undefined and must not be
> + * used.
> + */
> + union {
> + /**
> + * This member must be used for AV_CHANNEL_ORDER_NATIVE.
> + * It is a bitmask, where the position of each set bit means that the
> + * AVChannel with the corresponding value is present.
> + *
> + * I.e. when (mask & (1 << AV_CHAN_FOO)) is non-zero, then
> AV_CHAN_FOO
> + * is present in the layout. Otherwise it is not present.
> + *
> + * @note when a channel layout using a bitmask is constructed or
> + * modified manually (i.e. not using any of the av_channel_layout_*
> + * functions), the code doing it must ensure that the number of set
> bits
> + * is equal to nb_channels.
> + */
> + uint64_t mask;
> + /**
> + * This member must be used when the channel order is
> + * AV_CHANNEL_ORDER_CUSTOM. It is a nb_channels-sized array, with
> each
> + * element signalling the presend of the AVChannel with the
> + * corresponding value.
> + *
> + * I.e. when map[i] is equal to AV_CHAN_FOO, then AV_CH_FOO is the
> i-th
> + * channel in the audio data.
> + */
> + enum AVChannel *map;
> + } u;
> +} AVChannelLayout;
> +
> +#define AV_CHANNEL_LAYOUT_MONO \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 1, .u = { .mask =
> AV_CH_LAYOUT_MONO }}
These macros can only be used to init structures. This is unusual for
macros in ALL_CAPS, and therefore it needs to be documented.
> +#define AV_CHANNEL_LAYOUT_STEREO \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 2, .u = { .mask =
> AV_CH_LAYOUT_STEREO }}
> +#define AV_CHANNEL_LAYOUT_2POINT1 \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 3, .u = { .mask =
> AV_CH_LAYOUT_2POINT1 }}
> +#define AV_CHANNEL_LAYOUT_2_1 \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 3, .u = { .mask =
> AV_CH_LAYOUT_2_1 }}
> +#define AV_CHANNEL_LAYOUT_SURROUND \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 3, .u = { .mask =
> AV_CH_LAYOUT_SURROUND }}
> +#define AV_CHANNEL_LAYOUT_3POINT1 \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 4, .u = { .mask =
> AV_CH_LAYOUT_3POINT1 }}
> +#define AV_CHANNEL_LAYOUT_4POINT0 \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 4, .u = { .mask =
> AV_CH_LAYOUT_4POINT0 }}
> +#define AV_CHANNEL_LAYOUT_4POINT1 \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 5, .u = { .mask =
> AV_CH_LAYOUT_4POINT1 }}
> +#define AV_CHANNEL_LAYOUT_2_2 \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 4, .u = { .mask =
> AV_CH_LAYOUT_2_2 }}
> +#define AV_CHANNEL_LAYOUT_QUAD \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 4, .u = { .mask =
> AV_CH_LAYOUT_QUAD }}
> +#define AV_CHANNEL_LAYOUT_5POINT0 \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 5, .u = { .mask =
> AV_CH_LAYOUT_5POINT0 }}
> +#define AV_CHANNEL_LAYOUT_5POINT1 \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 6, .u = { .mask =
> AV_CH_LAYOUT_5POINT1 }}
> +#define AV_CHANNEL_LAYOUT_5POINT0_BACK \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 5, .u = { .mask =
> AV_CH_LAYOUT_5POINT0_BACK }}
> +#define AV_CHANNEL_LAYOUT_5POINT1_BACK \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 6, .u = { .mask =
> AV_CH_LAYOUT_5POINT1_BACK }}
> +#define AV_CHANNEL_LAYOUT_6POINT0 \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 6, .u = { .mask =
> AV_CH_LAYOUT_6POINT0 }}
> +#define AV_CHANNEL_LAYOUT_6POINT0_FRONT \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 6, .u = { .mask =
> AV_CH_LAYOUT_6POINT0_FRONT }}
> +#define AV_CHANNEL_LAYOUT_HEXAGONAL \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 6, .u = { .mask =
> AV_CH_LAYOUT_HEXAGONAL }}
> +#define AV_CHANNEL_LAYOUT_6POINT1 \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 7, .u = { .mask =
> AV_CH_LAYOUT_6POINT1 }}
> +#define AV_CHANNEL_LAYOUT_6POINT1_BACK \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 7, .u = { .mask =
> AV_CH_LAYOUT_6POINT1_BACK }}
> +#define AV_CHANNEL_LAYOUT_6POINT1_FRONT \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 7, .u = { .mask =
> AV_CH_LAYOUT_6POINT1_FRONT }}
> +#define AV_CHANNEL_LAYOUT_7POINT0 \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 7, .u = { .mask =
> AV_CH_LAYOUT_7POINT0 }}
> +#define AV_CHANNEL_LAYOUT_7POINT0_FRONT \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 7, .u = { .mask =
> AV_CH_LAYOUT_7POINT0_FRONT }}
> +#define AV_CHANNEL_LAYOUT_7POINT1 \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 8, .u = { .mask =
> AV_CH_LAYOUT_7POINT1 }}
> +#define AV_CHANNEL_LAYOUT_7POINT1_WIDE \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 8, .u = { .mask =
> AV_CH_LAYOUT_7POINT1_WIDE }}
> +#define AV_CHANNEL_LAYOUT_7POINT1_WIDE_BACK \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 8, .u = { .mask =
> AV_CH_LAYOUT_7POINT1_WIDE_BACK }}
> +#define AV_CHANNEL_LAYOUT_OCTAGONAL \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 8, .u = { .mask =
> AV_CH_LAYOUT_OCTAGONAL }}
> +#define AV_CHANNEL_LAYOUT_HEXADECAGONAL \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 16, .u = { .mask =
> AV_CH_LAYOUT_HEXAGONAL }}
> +#define AV_CHANNEL_LAYOUT_STEREO_DOWNMIX \
> + { .order = AV_CHANNEL_ORDER_NATIVE, .nb_channels = 2, .u = { .mask =
> AV_CH_LAYOUT_STEREO_DOWNMIX }}
> +
> +#if FF_API_OLD_CHANNEL_LAYOUT
> /**
> * Return a channel layout id that matches name, or 0 if no match is found.
> *
> @@ -138,7 +329,10 @@ enum AVMatrixEncoding {
> * AV_CH_* macros).
> *
> * Example: "stereo+FC" = "2c+FC" = "2c+1c" = "0x7"
> + *
> + * @deprecated use av_channel_layout_from_string()
> */
> +attribute_deprecated
> uint64_t av_get_channel_layout(const char *name);
>
> /**
> @@ -161,7 +355,9 @@ int av_get_extended_channel_layout(const char *name,
> uint64_t* channel_layout, i
> *
> * @param buf put here the string containing the channel layout
> * @param buf_size size in bytes of the buffer
> + * @deprecated use av_channel_layout_describe()
> */
> +attribute_deprecated
> void av_get_channel_layout_string(char *buf, int buf_size, int nb_channels,
> uint64_t channel_layout);
>
> struct AVBPrint;
> @@ -172,12 +368,17 @@ void av_bprint_channel_layout(struct AVBPrint *bp, int
> nb_channels, uint64_t cha
>
> /**
> * Return the number of channels in the channel layout.
> + * @deprecated use AVChannelLayout.nb_channels
> */
> +attribute_deprecated
> int av_get_channel_layout_nb_channels(uint64_t channel_layout);
>
> /**
> * Return default channel layout for a given number of channels.
> + *
> + * @deprecated use av_channel_layout_default()
> */
> +attribute_deprecated
> int64_t av_get_default_channel_layout(int nb_channels);
>
> /**
> @@ -188,20 +389,28 @@ int64_t av_get_default_channel_layout(int nb_channels);
> *
> * @return index of channel in channel_layout on success, a negative AVERROR
> * on error.
> + *
> + * @deprecated use av_channel_layout_channel_index()
> */
> +attribute_deprecated
> int av_get_channel_layout_channel_index(uint64_t channel_layout,
> uint64_t channel);
>
> /**
> * Get the channel with the given index in channel_layout.
> + * @deprecated use av_channel_layout_get_channel()
> */
> +attribute_deprecated
> uint64_t av_channel_layout_extract_channel(uint64_t channel_layout, int
> index);
>
> /**
> * Get the name of a given channel.
> *
> * @return channel name on success, NULL on error.
> + *
> + * @deprecated use av_channel_name()
> */
> +attribute_deprecated
> const char *av_get_channel_name(uint64_t channel);
>
> /**
> @@ -210,6 +419,7 @@ const char *av_get_channel_name(uint64_t channel);
> * @param channel a channel layout with a single channel
> * @return channel description on success, NULL on error
> */
> +attribute_deprecated
> const char *av_get_channel_description(uint64_t channel);
>
> /**
> @@ -221,9 +431,158 @@ const char *av_get_channel_description(uint64_t
> channel);
> * @return 0 if the layout exists,
> * <0 if index is beyond the limits
> */
> +attribute_deprecated
> int av_get_standard_channel_layout(unsigned index, uint64_t *layout,
> const char **name);
>
> +#endif
> +
> +/**
> + * This is the inverse function of @ref av_channel_from_string().
> + *
> + * @return a string describing a given channel, or NULL if not found.
> + */
> +const char *av_channel_name(enum AVChannel channel);
> +
> +/**
> + * This is the inverse function of @ref av_channel_name().
> + *
> + * @return a channel described by the given string, or a negative AVERROR
> value.
> + */
> +int av_channel_from_string(const char *name);
> +
> +/**
> + * Initialize a native channel layout from a bitmask indicating which
> channels
> + * are present.
> + *
> + * @note channel_layout should be properly allocated as described above.
> + *
> + * @param channel_layout the layout structure to be initialized
> + * @param mask bitmask describing the channel layout
> + */
> +void av_channel_layout_from_mask(AVChannelLayout *channel_layout, uint64_t
> mask);
> +
> +/**
> + * Initialize a channel layout from a given string description.
> + * The input string can be represented by:
> + * - the formal channel layout name (returned by
> av_channel_layout_describe())
> + * - single or multiple channel names (returned by av_channel_name()
> + * or concatenated with "+")
> + * - a hexadecimal value of a channel layout (eg. "0x4")
> + * - the number of channels with default layout (eg. "5")
> + * - the number of unordered channels (eg. "4 channels")
> + *
> + * @note channel_layout should be properly allocated as described above.
> + *
> + * @param channel_layout input channel layout
> + * @param str string describing the channel layout
> + * @return 0 channel layout was detected, AVERROR_INVALIDATATA otherwise
> + */
> +int av_channel_layout_from_string(AVChannelLayout *channel_layout,
> + const char *str);
> +
> +/**
> + * Get the default channel layout for a given number of channels.
> + *
> + * @note channel_layout should be properly allocated as described above.
> + *
> + * @param channel_layout the layout structure to be initialized
> + * @param nb_channels number of channels
> + */
> +void av_channel_layout_default(AVChannelLayout *ch_layout, int nb_channels);
unsigned nb_channels
> +
> +/**
> + * Free any allocated data in the channel layout and reset the channel
> + * count to 0.
> + *
> + * @note this only used for structure initialization and for freeing the
> + * allocated memory for AV_CHANNEL_ORDER_CUSTOM order.
> + *
> + * @param channel_layout the layout structure to be uninitialized
> + */
> +void av_channel_layout_uninit(AVChannelLayout *channel_layout);
> +
> +/**
> + * Make a copy of a channel layout. This differs from just assigning src to
> dst
> + * in that it allocates and copies the map for AV_CHANNEL_ORDER_CUSTOM.
> + *
> + * @note the destination channel_layout will be always uninitialized before
> copy.
> + *
> + * @param dst destination channel layout
> + * @param src source channel layout
> + * @return 0 on success, a negative AVERROR on error.
> + */
> +int av_channel_layout_copy(AVChannelLayout *dst, const AVChannelLayout *src);
> +
> +/**
> + * Get a human-readable string describing the channel layout properties.
> + *
> + * @note The returned string is allocated with av_malloc(),
> + * and must be freed by the caller with av_free().
The relation between av_channel_layout_copy() and
av_channel_layout_from_string() needs to be documented.
> + *
> + * @param channel_layout channel layout to be described
> + * @return a string describing the structure or NULL on failure in the same
> + * format that is accepted by @ref av_channel_layout_from_string().
> + */
> +char *av_channel_layout_describe(const AVChannelLayout *channel_layout);
> +
> +/**
> + * Get the channel with the given index in a channel layout.
> + *
> + * @param channel_layout input channel layout
> + * @return channel with the index idx in channel_layout on success or a
> negative
> + * AVERROR on failure (if idx is not valid or the channel
> order
> + * is unspecified)
> + */
> +int av_channel_layout_get_channel(const AVChannelLayout *channel_layout, int
> idx);
unsigned idx
But do we really need this as part of the API?
> +
> +/**
> + * Get the index of a given channel in a channel layout. In case multiple
> + * channels are found, only the first match will be returned.
> + *
> + * @param channel_layout input channel layout
> + * @return index of channel in channel_layout on success or a negative
> number if
> + * channel is not present in channel_layout.
> + */
> +int av_channel_layout_channel_index(const AVChannelLayout *channel_layout,
> + enum AVChannel channel);
Same: do we reall yneed this?
> +
> +/**
> + * Find out what channels from a given set are present in a channel layout,
> + * without regard for their positions.
> + *
> + * @param channel_layout input channel layout
> + * @param mask a combination of AV_CH_* representing a set of channels
> + * @return a bitfield representing all the channels from mask that are
> present
> + * in channel_layout
> + */
> +uint64_t av_channel_layout_subset(const AVChannelLayout *channel_layout,
> + uint64_t mask);
Same.
> +
> +/**
> + * Check whether a channel layout is valid, i.e. can possibly describe audio
> + * data.
> + *
> + * @param channel_layout input channel layout
> + * @return 1 if channel_layout is valid, 0 otherwise.
> + */
> +int av_channel_layout_check(const AVChannelLayout *channel_layout);
> +
> +/**
> + * Check whether two channel layouts are semantically the same, i.e. the same
> + * channels are present on the same positions in both.
> + *
> + * If one of the channel layouts is AV_CHANNEL_ORDER_UNSPEC, while the other
> is
> + * not, they are considered to be unequal. If both are
> AV_CHANNEL_ORDER_UNSPEC,
> + * they are considered equal iff the channel counts are the same in both.
> + *
> + * @param chl input channel layout
> + * @param chl1 input channel layout
> + * @return 0 if chl and chl1 are equal, 1 or -1 if they are not equal but are
> + * same order. -2 code if they do not match some other way.
> + */
> +int av_channel_layout_compare(const AVChannelLayout *chl, const
> AVChannelLayout *chl1);
> +
> /**
> * @}
> * @}
> diff --git a/libavutil/version.h b/libavutil/version.h
> index 27d663baf1..5e025c463f 100644
> --- a/libavutil/version.h
> +++ b/libavutil/version.h
> @@ -129,6 +129,9 @@
> #ifndef FF_API_PSEUDOPAL
> #define FF_API_PSEUDOPAL (LIBAVUTIL_VERSION_MAJOR < 57)
> #endif
> +#ifndef FF_API_OLD_CHANNEL_LAYOUT
> +#define FF_API_OLD_CHANNEL_LAYOUT (LIBAVUTIL_VERSION_MAJOR < 58)
> +#endif
>
>
> /**
Regards,
--
Nicolas George
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