> From: "Paul B Mahol" <one...@gmail.com>
> To: "FFmpeg development discussions and patches" <ffmpeg-devel@ffmpeg.org>
> Cc: "Damien Riegel" <damien.rie...@savoirfairelinux.com>, "Patrick Keroulas"
> <patrick.kerou...@savoirfairelinux.com>
> Sent: Wednesday, April 11, 2018 2:47:40 AM
> Subject: Re: [FFmpeg-devel] [PATCH v1 2/3] avcodec/bitpacked: add interlace
> support
> On 4/10/18, Patrick Keroulas <patrick.kerou...@savoirfairelinux.com> wrote:
> > From: Damien Riegel <damien.rie...@savoirfairelinux.com>
> > This codec is already capable of depacking some combinations of pixel
> > formats and depth as defined in the RFC4175. The only difference between
> > progressive and interlace is that either a packet will contain the whole
> > frame, or only a field of the frame.
> > As FFmpeg is not capable of handling fields only and recompose an
> > interlaced frame from that, it has to be done by the codec. To achieve
> > that, it must use two AVPacket: one for each field (top and bottom).
> This is lie, FFmpeg handle fields only just fine.
We should have specified "There is no mechanism for interlaced frames
reconstruction at the rtp demux level, so it has to be handled by the codec".
Or do you mean that there is no point recomposing frames from fields?
Any other comment/hint on the implementation?
> > Signed-off-by: Damien Riegel <damien.rie...@savoirfairelinux.com>
> > Signed-off-by: Patrick Keroulas <patrick.kerou...@savoirfairelinux.com>
> > ---
> > libavcodec/avcodec.h | 4 +++
> > libavcodec/bitpacked.c | 76
> > ++++++++++++++++++++++++++++++++++++++++++--------
> > 2 files changed, 68 insertions(+), 12 deletions(-)
> > diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
> > index fb0c6fa..350e8d9 100644
> > --- a/libavcodec/avcodec.h
> > +++ b/libavcodec/avcodec.h
> > @@ -1480,6 +1480,10 @@ typedef struct AVPacket {
> > */
> > #define AV_PKT_FLAG_DISPOSABLE 0x0010
> > +/**
> > + * The packet contains a top field.
> > + */
> > +#define AV_PKT_FLAG_TOP_FIELD 0x0010
This flag will be fixed.
> > enum AVSideDataParamChangeFlags {
> > AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_COUNT = 0x0001,
> > diff --git a/libavcodec/bitpacked.c b/libavcodec/bitpacked.c
> > index 85d4bdd..d81703d 100644
> > --- a/libavcodec/bitpacked.c
> > +++ b/libavcodec/bitpacked.c
> > @@ -33,15 +33,19 @@
> > struct BitpackedContext {
> > int (*decode)(AVCodecContext *avctx, AVFrame *frame,
> > - AVPacket *pkt);
> > + AVPacket *pkt, int top_field);
> > + AVPacket *first_field_pkt;
> > };
> > /* For this format, it's a simple passthrough */
> > static int bitpacked_decode_uyvy422(AVCodecContext *avctx, AVFrame *frame,
> > - AVPacket *avpkt)
> > + AVPacket *avpkt, int top_field)
> > {
> > int ret;
> > + if (frame->interlaced_frame)
> > + return AVERROR_PATCHWELCOME;
> > +
> > /* there is no need to copy as the data already match
> > * a known pixel format */
> > frame->buf[0] = av_buffer_ref(avpkt->buf);
> > @@ -56,17 +60,22 @@ static int bitpacked_decode_uyvy422(AVCodecContext
> > *avctx, AVFrame *frame,
> > }
> > static int bitpacked_decode_yuv422p10(AVCodecContext *avctx, AVFrame
> > *frame,
> > - AVPacket *avpkt)
> > + AVPacket *avpkt, int top_field)
> > {
> > uint64_t frame_size = (uint64_t)avctx->width * (uint64_t)avctx->height
> > * 20;
> > uint64_t packet_size = (uint64_t)avpkt->size * 8;
> > + int interlaced = frame->interlaced_frame;
> > GetBitContext bc;
> > uint16_t *y, *u, *v;
> > int ret, i, j;
> > -
> > - if (frame_size > packet_size)
> > + /* check packet size depending on the interlaced/progressive format */
> > + if (interlaced) {
> > + if ((frame_size >> 1) > packet_size)
> > + return AVERROR_INVALIDDATA;
> > + } else if (frame_size > packet_size) {
> > return AVERROR_INVALIDDATA;
> > + }
> > if (avctx->width % 2)
> > return AVERROR_PATCHWELCOME;
> > @@ -75,7 +84,18 @@ static int bitpacked_decode_yuv422p10(AVCodecContext
> > *avctx, AVFrame *frame,
> > if (ret)
> > return ret;
> > - for (i = 0; i < avctx->height; i++) {
> > + /*
> > + * if the frame is interlaced, the avpkt we are getting is either the
> > top
> > + * or the bottom field. If it's the bottom field, it contains all the
> > odd
> > + * lines of the recomposed frame, so we start at offset 1.
> > + */
> > + i = (interlaced && !top_field) ? 1 : 0;
> > +
> > + /*
> > + * Packets from interlaced frames contain either even lines, or odd
> > + * lines, so increment by two in that case.
> > + */
> > + for (; i < avctx->height; interlaced ? i += 2 : i++) {
> > y = (uint16_t*)(frame->data[0] + i * frame->linesize[0]);
> > u = (uint16_t*)(frame->data[1] + i * frame->linesize[1]);
> > v = (uint16_t*)(frame->data[2] + i * frame->linesize[2]);
> > @@ -100,13 +120,20 @@ static av_cold int
> > bitpacked_init_decoder(AVCodecContext *avctx)
> > if (avctx->codec_tag == MKTAG('U', 'Y', 'V', 'Y')) {
> > if (avctx->bits_per_coded_sample == 16 &&
> > - avctx->pix_fmt == AV_PIX_FMT_UYVY422)
> > + avctx->pix_fmt == AV_PIX_FMT_UYVY422) {
> > +
> > + if (avctx->field_order > AV_FIELD_PROGRESSIVE) {
> > + av_log(avctx, AV_LOG_ERROR, "interlaced not yet supported
> > for 8-bit\n");
> > + return AVERROR_PATCHWELCOME;
> > + }
> > +
> > bc->decode = bitpacked_decode_uyvy422;
> > - else if (avctx->bits_per_coded_sample == 20 &&
> > - avctx->pix_fmt == AV_PIX_FMT_YUV422P10)
> > + } else if (avctx->bits_per_coded_sample == 20 &&
> > + avctx->pix_fmt == AV_PIX_FMT_YUV422P10) {
> > bc->decode = bitpacked_decode_yuv422p10;
> > - else
> > + } else {
> > return AVERROR_INVALIDDATA;
> > + }
> > } else {
> > return AVERROR_INVALIDDATA;
> > }
> > @@ -120,24 +147,49 @@ static int bitpacked_decode(AVCodecContext *avctx,
> > void *data, int *got_frame,
> > struct BitpackedContext *bc = avctx->priv_data;
> > int buf_size = avpkt->size;
> > AVFrame *frame = data;
> > + int top_field = 0;
> > int res;
> > frame->pict_type = AV_PICTURE_TYPE_I;
> > frame->key_frame = 1;
> > + if (avctx->field_order != AV_FIELD_PROGRESSIVE) {
> > + top_field = avpkt->flags & AV_PKT_FLAG_TOP_FIELD;
> > + frame->interlaced_frame = 1;
> > + frame->top_field_first = 1;
> > + }
> > +
> > if (avctx->pix_fmt == AV_PIX_FMT_YUV422P10) {
> > res = ff_get_buffer(avctx, frame, 0);
> > if (res < 0)
> > return res;
> > }
> > - res = bc->decode(avctx, frame, avpkt);
> > + if (frame->interlaced_frame) {
> > +
> > + if (top_field) {
> > + bc->first_field_pkt = av_packet_clone(avpkt);
> > + return 0;
> > +
> > + } else if (bc->first_field_pkt) {
> > + /* Combine the 2 fields in a single frame.
> > + * N fields/s give N/2 frames/s. */
> > + res = bc->decode(avctx, frame, bc->first_field_pkt, 1);
> > + res += bc->decode(avctx, frame, avpkt, 0);
> > +
> > + av_packet_free(&bc->first_field_pkt);
> > + } else {
> > + return 0;
> > + }
> > + } else {
> > + res = bc->decode(avctx, frame, avpkt, 0);
> > + }
> > +
> > if (res)
> > return res;
> > *got_frame = 1;
> > return buf_size;
> > -
> > }
> > AVCodec ff_bitpacked_decoder = {
> > --
> > 2.7.4
> > _______________________________________________
> > ffmpeg-devel mailing list
> > ffmpeg-devel@ffmpeg.org
> > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
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