On Fri, May 19, 2023 at 4:41 PM Zhao Zhili <quinkbl...@foxmail.com> wrote:
>
> From: Zhao Zhili <zhiliz...@tencent.com>
>
> start_code_size depends on whether PS comes from out-of-band or
> in-band. Make the code more readable.
> ---
> libavcodec/h264_mp4toannexb_bsf.c | 34 ++++++++++++++++++++++++-------
> 1 file changed, 27 insertions(+), 7 deletions(-)
>
> diff --git a/libavcodec/h264_mp4toannexb_bsf.c
> b/libavcodec/h264_mp4toannexb_bsf.c
> index d11be455c2..7dce1ae9b6 100644
> --- a/libavcodec/h264_mp4toannexb_bsf.c
> +++ b/libavcodec/h264_mp4toannexb_bsf.c
> @@ -43,10 +43,26 @@ typedef struct H264BSFContext {
> int extradata_parsed;
> } H264BSFContext;
>
> +enum PsSource {
> + PS_OUT_OF_BAND = -1,
> + PS_NONE = 0,
> + PS_IN_BAND = 1,
> +};
> +
> static void count_or_copy(uint8_t **out, uint64_t *out_size,
> - const uint8_t *in, int in_size, int ps, int copy)
> + const uint8_t *in, int in_size, enum PsSource ps,
> int copy)
> {
> - uint8_t start_code_size = ps < 0 ? 0 : *out_size == 0 || ps ? 4 : 3;
> + uint8_t start_code_size;
> +
> + if (ps == PS_OUT_OF_BAND)
> + /* start code already present in out-of-band ps data, so don't need
> to
> + * add it manually again
> + */
> + start_code_size = 0;
> + else if (ps == PS_IN_BAND || *out_size == 0)
> + start_code_size = 4;
> + else
> + start_code_size = 3;
I prefer the original style, they are shorter and more concise
>
> if (copy) {
> memcpy(*out + start_code_size, in, in_size);
> @@ -202,6 +218,7 @@ static int h264_mp4toannexb_filter(AVBSFContext *ctx,
> AVPacket *opkt)
>
> do {
> uint32_t nal_size = 0;
> + enum PsSource ps;
>
> /* possible overread ok due to padding */
> for (int i = 0; i < s->length_size; i++)
> @@ -230,7 +247,7 @@ static int h264_mp4toannexb_filter(AVBSFContext *ctx,
> AVPacket *opkt)
> if (!s->sps_size) {
> LOG_ONCE(ctx, AV_LOG_WARNING, "SPS not present in
> the stream, nor in AVCC, stream may be unreadable\n");
> } else {
> - count_or_copy(&out, &out_size, s->sps, s->sps_size,
> -1, j);
> + count_or_copy(&out, &out_size, s->sps, s->sps_size,
> PS_OUT_OF_BAND, j);
> sps_seen = 1;
> }
> }
> @@ -246,19 +263,22 @@ static int h264_mp4toannexb_filter(AVBSFContext *ctx,
> AVPacket *opkt)
> if (new_idr && unit_type == H264_NAL_IDR_SLICE && !sps_seen &&
> !pps_seen) {
> if (ctx->par_out->extradata)
> count_or_copy(&out, &out_size, ctx->par_out->extradata,
> - ctx->par_out->extradata_size, -1, j);
> + ctx->par_out->extradata_size,
> PS_OUT_OF_BAND, j);
> new_idr = 0;
> /* if only SPS has been seen, also insert PPS */
> } else if (new_idr && unit_type == H264_NAL_IDR_SLICE &&
> sps_seen && !pps_seen) {
> if (!s->pps_size) {
> LOG_ONCE(ctx, AV_LOG_WARNING, "PPS not present in the
> stream, nor in AVCC, stream may be unreadable\n");
> } else {
> - count_or_copy(&out, &out_size, s->pps, s->pps_size, -1,
> j);
> + count_or_copy(&out, &out_size, s->pps, s->pps_size,
> PS_OUT_OF_BAND, j);
> }
> }
>
> - count_or_copy(&out, &out_size, buf, nal_size,
> - unit_type == H264_NAL_SPS || unit_type ==
> H264_NAL_PPS, j);
> + if (unit_type == H264_NAL_SPS || unit_type == H264_NAL_PPS)
> + ps = PS_IN_BAND;
> + else
> + ps = PS_NONE;
> + count_or_copy(&out, &out_size, buf, nal_size, ps, j);
> if (!new_idr && unit_type == H264_NAL_SLICE) {
> new_idr = 1;
> sps_seen = 0;
> --
> 2.25.1
>
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--
=======================================
Jun zhao/赵军
+++++++++++++++++++++++++++++++++++++++
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