[FFmpeg-devel] [PATCH] avformat/hlsenc: support CODECS Attribute in hevc EXT-X-STREAM-INF

[Steven Liu]

> 在 2020年10月12日，21:45，Guangxin Xu <oddstone at gmail.com> 写道：
> 
> 
> 
> On Mon, Oct 12, 2020 at 5:18 PM Steven Liu <lq at chinaffmpeg.org> wrote:
> fix ticket: 8904
> parse the SPS from extradata and get profile_tier_level
> write the profile_tier_level info into CODECS Attribute
> 
> reference to :https://developer.apple.com/documentation/http_live_streaming/hls_authoring_specification_for_apple_devices/hls_authoring_specification_for_apple_devices_appendixes
> 
> Signed-off-by: Steven Liu <lq at chinaffmpeg.org>
> ---
>  libavformat/hlsenc.c | 41 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 41 insertions(+)
> 
> diff --git a/libavformat/hlsenc.c b/libavformat/hlsenc.c
> index cb31d6aed7..574d9f81e9 100644
> --- a/libavformat/hlsenc.c
> +++ b/libavformat/hlsenc.c
> @@ -337,6 +337,43 @@ static void write_codec_attr(AVStream *st, VariantStream *vs)
>          } else {
>              goto fail;
>          }
> +    } else if (st->codecpar->codec_id == AV_CODEC_ID_HEVC) {
> +        uint8_t *data = st->codecpar->extradata;
> +        int i = 0;
> +        int profile = FF_PROFILE_UNKNOWN;
> +        int level = FF_LEVEL_UNKNOWN;
> +
> +        if (st->codecpar->profile != FF_PROFILE_UNKNOWN)
> +            profile = st->codecpar->profile;
> +        if (st->codecpar->level != FF_LEVEL_UNKNOWN)
> +            level = st->codecpar->level;
> +
> +        while (data && (data - st->codecpar->extradata) < st->codecpar->extradata_size) {
> +            /* get HEVC SPS NAL and seek to profile_tier_level */
> +            if (data && (data[0] | data[1] | data[2]) == 0 && data[3] == 1 && ((data[4] & 0x42) == 0x42)) {
> Read beyond the boundary if data + 1 - st->codecpar->extradata  >=    st->codecpar->extradata_size 
ok
> Is it possible reuese ff_hevc_decode_extradata here?
it is in libavcodec, i don’t think depend libavcodec in hlsenc is a good way, so parse sps here.
> 
> +                int rbsp_byte_size;
> +                data += 7;
> +                /* process by reference General NAL unit syntax */
> +                profile = *data & 0x1f;
> +                rbsp_byte_size = st->codecpar->extradata_size - (data - st->codecpar->extradata);
> +                for (i = 0; i < rbsp_byte_size; i++, data++) {
> +                    if (data[0] == 0 && data[1] == 0 && data[2] == 3) {
> +                        data += 2;
> +                        i++;
> +                    }
> +                    /* skip 8 + 32 + 4 + 43 + 1 bit */
> +                    if (i == 11)
> +                        level = *data;
> +                }
> +                break;
> +            }
> +            data++;
> +        }
> +        if (st->codecpar->codec_tag == MKTAG('h','v','c','1') &&
> +            profile != FF_PROFILE_UNKNOWN &&
> +            level != FF_LEVEL_UNKNOWN) {
> +            snprintf(attr, sizeof(attr), "%s.%d.4.L%d.B01", av_fourcc2str(st->codecpar->codec_tag), profile, level);
> +        }
>      } else if (st->codecpar->codec_id == AV_CODEC_ID_MP2) {
>          snprintf(attr, sizeof(attr), "mp4a.40.33");
>      } else if (st->codecpar->codec_id == AV_CODEC_ID_MP3) {
> @@ -2247,6 +2284,10 @@ static int hls_write_header(AVFormatContext *s)
>                  continue;
>              }
>              avpriv_set_pts_info(outer_st, inner_st->pts_wrap_bits, inner_st->time_base.num, inner_st->time_base.den);
> +            if (outer_st->codecpar->codec_id == AV_CODEC_ID_HEVC &&
> +                outer_st->codecpar->codec_tag != MKTAG('h','v','c','1')) {
> +                av_log(s, AV_LOG_WARNING, "Stream HEVC is not hvc1, you should use tag:v hvc1 to set it.\n");
> +            }
>              write_codec_attr(outer_st, vs);
> 
>          }
> -- 
> 2.25.0
> 
> 
> 
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Thanks
Steven