Re: [FFmpeg-devel] [PATCH 1/2] avformat/flvenc: Add support for HEVC over flv in muxer

[Lance Wang <lance.lmwang@gmail.com>]

On Thu, Apr 6, 2023 at 8:14 PM Steven Liu <lq@chinaffmpeg.org> wrote:

> Implements HEVC according to enhanced RTMP spec found at
> https://github.com/veovera/enhanced-rtmp
>
>
I think It's document or draft and not specs, I haven't heard any
information for the
veovera software organization. So before implementation, please prove it's
recognized authority.  Please see rfc2026.



> And it has beed supported by OBS, Simple Realtime Server.
> And the Enhancing FLV documentation Contributors include
> Jean-Baptiste Kempf (FFmpeg, VideoLAN).
> So this should be support by ffmpeg too.
>
> Signed-off-by: Steven Liu <lq@chinaffmpeg.org>
> ---
>  libavformat/flv.h    | 16 ++++++++++++++
>  libavformat/flvenc.c | 50 +++++++++++++++++++++++++++++++++-----------
>  2 files changed, 54 insertions(+), 12 deletions(-)
>
> diff --git a/libavformat/flv.h b/libavformat/flv.h
> index 3571b90279..44d3b04ff9 100644
> --- a/libavformat/flv.h
> +++ b/libavformat/flv.h
> @@ -35,6 +35,12 @@
>
>  #define FLV_VIDEO_FRAMETYPE_OFFSET   4
>
> +/* Extended VideoTagHeader
> + * defined in reference link:
> + *
> https://github.com/veovera/enhanced-rtmp/blob/main/enhanced-rtmp-v1.pdf
> + * */
> +#define FLV_IS_EX_HEADER          0x80
> +
>  /* bitmasks to isolate specific values */
>  #define FLV_AUDIO_CHANNEL_MASK    0x01
>  #define FLV_AUDIO_SAMPLESIZE_MASK 0x02
> @@ -110,6 +116,16 @@ enum {
>      FLV_CODECID_H264    = 7,
>      FLV_CODECID_REALH263= 8,
>      FLV_CODECID_MPEG4   = 9,
> +    FLV_CODECID_HEVC    = 10,
> +};
> +
> +enum {
> +    PacketTypeSequenceStart         = 0,
> +    PacketTypeCodedFrames           = 1,
> +    PacketTypeSequenceEnd           = 2,
> +    PacketTypeCodedFramesX          = 3,
> +    PacketTypeMetadata              = 4,
> +    PacketTypeMPEG2TSSequenceStart  = 5,
>  };
>
>  enum {
> diff --git a/libavformat/flvenc.c b/libavformat/flvenc.c
> index 64ea554dad..15a0f573f3 100644
> --- a/libavformat/flvenc.c
> +++ b/libavformat/flvenc.c
> @@ -28,6 +28,7 @@
>  #include "libavcodec/mpeg4audio.h"
>  #include "avio.h"
>  #include "avc.h"
> +#include "hevc.h"
>  #include "avformat.h"
>  #include "flv.h"
>  #include "internal.h"
> @@ -46,6 +47,7 @@ static const AVCodecTag flv_video_codec_ids[] = {
>      { AV_CODEC_ID_VP6,      FLV_CODECID_VP6 },
>      { AV_CODEC_ID_VP6A,     FLV_CODECID_VP6A },
>      { AV_CODEC_ID_H264,     FLV_CODECID_H264 },
> +    { AV_CODEC_ID_HEVC,     FLV_CODECID_HEVC },
>      { AV_CODEC_ID_NONE,     0 }
>  };
>
> @@ -492,7 +494,7 @@ static void flv_write_codec_header(AVFormatContext* s,
> AVCodecParameters* par, i
>      FLVContext *flv = s->priv_data;
>
>      if (par->codec_id == AV_CODEC_ID_AAC || par->codec_id ==
> AV_CODEC_ID_H264
> -            || par->codec_id == AV_CODEC_ID_MPEG4) {
> +            || par->codec_id == AV_CODEC_ID_MPEG4 || par->codec_id ==
> AV_CODEC_ID_HEVC) {
>          int64_t pos;
>          avio_w8(pb,
>                  par->codec_type == AVMEDIA_TYPE_VIDEO ?
> @@ -535,10 +537,19 @@ static void flv_write_codec_header(AVFormatContext*
> s, AVCodecParameters* par, i
>              }
>              avio_write(pb, par->extradata, par->extradata_size);
>          } else {
> -            avio_w8(pb, par->codec_tag | FLV_FRAME_KEY); // flags
> -            avio_w8(pb, 0); // AVC sequence header
> -            avio_wb24(pb, 0); // composition time
> -            ff_isom_write_avcc(pb, par->extradata, par->extradata_size);
> +            if (par->codec_id == AV_CODEC_ID_HEVC) {
> +                avio_w8(pb, FLV_IS_EX_HEADER | PacketTypeSequenceStart);
> // ExVideoTagHeader mode with PacketTypeSequenceStart
> +                avio_write(pb, "hvc1", 4);
> +            } else {
> +                avio_w8(pb, par->codec_tag | FLV_FRAME_KEY); // flags
> +                avio_w8(pb, 0); // AVC sequence header
> +                avio_wb24(pb, 0); // composition time
> +            }
> +
> +            if (par->codec_id == AV_CODEC_ID_HEVC)
> +                ff_isom_write_hvcc(pb, par->extradata,
> par->extradata_size, 0);
> +            else
> +                ff_isom_write_avcc(pb, par->extradata,
> par->extradata_size);
>          }
>          data_size = avio_tell(pb) - pos;
>          avio_seek(pb, -data_size - 10, SEEK_CUR);
> @@ -628,7 +639,8 @@ static int flv_init(struct AVFormatContext *s)
>                  return unsupported_codec(s, "Video", par->codec_id);
>
>              if (par->codec_id == AV_CODEC_ID_MPEG4 ||
> -                par->codec_id == AV_CODEC_ID_H263) {
> +                par->codec_id == AV_CODEC_ID_H263 ||
> +                par->codec_id == AV_CODEC_ID_HEVC) {
>                  int error = s->strict_std_compliance >
> FF_COMPLIANCE_UNOFFICIAL;
>                  av_log(s, error ? AV_LOG_ERROR : AV_LOG_WARNING,
>                         "Codec %s is not supported in the official FLV
> specification,\n", avcodec_get_name(par->codec_id));
> @@ -784,8 +796,11 @@ end:
>          for (i = 0; i < s->nb_streams; i++) {
>              AVCodecParameters *par = s->streams[i]->codecpar;
>              FLVStreamContext *sc = s->streams[i]->priv_data;
> -            if (par->codec_type == AVMEDIA_TYPE_VIDEO &&
> -                    (par->codec_id == AV_CODEC_ID_H264 || par->codec_id
> == AV_CODEC_ID_MPEG4))
> +            if (par->codec_id == AV_CODEC_ID_HEVC) {
> +                avio_w8(pb, 0x82);
> +                avio_write(pb, "hvc1", 4);
> +            } else if (par->codec_type == AVMEDIA_TYPE_VIDEO &&
> +                    (par->codec_id == AV_CODEC_ID_H264 || par->codec_id
> == AV_CODEC_ID_MPEG4 || par->codec_id == AV_CODEC_ID_HEVC))
>                  put_eos_tag(pb, sc->last_ts, par->codec_id);
>          }
>      }
> @@ -836,13 +851,13 @@ static int flv_write_packet(AVFormatContext *s,
> AVPacket *pkt)
>      if (par->codec_id == AV_CODEC_ID_VP6F || par->codec_id ==
> AV_CODEC_ID_VP6A ||
>          par->codec_id == AV_CODEC_ID_VP6  || par->codec_id ==
> AV_CODEC_ID_AAC)
>          flags_size = 2;
> -    else if (par->codec_id == AV_CODEC_ID_H264 || par->codec_id ==
> AV_CODEC_ID_MPEG4)
> +    else if (par->codec_id == AV_CODEC_ID_H264 || par->codec_id ==
> AV_CODEC_ID_MPEG4 || par->codec_id == AV_CODEC_ID_HEVC)
>          flags_size = 5;
>      else
>          flags_size = 1;
>
>      if (par->codec_id == AV_CODEC_ID_AAC || par->codec_id ==
> AV_CODEC_ID_H264
> -            || par->codec_id == AV_CODEC_ID_MPEG4) {
> +            || par->codec_id == AV_CODEC_ID_MPEG4 || par->codec_id ==
> AV_CODEC_ID_HEVC) {
>          size_t side_size;
>          uint8_t *side = av_packet_get_side_data(pkt,
> AV_PKT_DATA_NEW_EXTRADATA, &side_size);
>          if (side && side_size > 0 && (side_size != par->extradata_size ||
> memcmp(side, par->extradata, side_size))) {
> @@ -862,7 +877,7 @@ static int flv_write_packet(AVFormatContext *s,
> AVPacket *pkt)
>                 "Packets are not in the proper order with respect to
> DTS\n");
>          return AVERROR(EINVAL);
>      }
> -    if (par->codec_id == AV_CODEC_ID_H264 || par->codec_id ==
> AV_CODEC_ID_MPEG4) {
> +    if (par->codec_id == AV_CODEC_ID_H264 || par->codec_id ==
> AV_CODEC_ID_MPEG4 || par->codec_id == AV_CODEC_ID_HEVC) {
>          if (pkt->pts == AV_NOPTS_VALUE) {
>              av_log(s, AV_LOG_ERROR, "Packet is missing PTS\n");
>              return AVERROR(EINVAL);
> @@ -907,6 +922,10 @@ static int flv_write_packet(AVFormatContext *s,
> AVPacket *pkt)
>          if (par->extradata_size > 0 && *(uint8_t*)par->extradata != 1)
>              if ((ret = ff_avc_parse_nal_units_buf(pkt->data, &data,
> &size)) < 0)
>                  return ret;
> +    } else if (par->codec_id == AV_CODEC_ID_HEVC) {
> +        if (par->extradata_size > 0 && *(uint8_t*)par->extradata != 1)
> +            if ((ret = ff_hevc_annexb2mp4_buf(pkt->data, &data, &size, 0,
> NULL)) < 0)
> +                return ret;
>      } else if (par->codec_id == AV_CODEC_ID_AAC && pkt->size > 2 &&
>                 (AV_RB16(pkt->data) & 0xfff0) == 0xfff0) {
>          if (!s->streams[pkt->stream_index]->nb_frames) {
> @@ -968,7 +987,12 @@ static int flv_write_packet(AVFormatContext *s,
> AVPacket *pkt)
>          avio_wb32(pb, data_size + 11);
>      } else {
>          av_assert1(flags>=0);
> -        avio_w8(pb,flags);
> +        if (par->codec_id == AV_CODEC_ID_HEVC) {
> +            avio_w8(pb, FLV_IS_EX_HEADER | PacketTypeCodedFrames); //
> ExVideoTagHeader mode with PacketTypeCodedFrames
> +            avio_write(pb, "hvc1", 4);
> +        } else {
> +            avio_w8(pb, flags);
> +        }
>          if (par->codec_id == AV_CODEC_ID_VP6)
>              avio_w8(pb,0);
>          if (par->codec_id == AV_CODEC_ID_VP6F || par->codec_id ==
> AV_CODEC_ID_VP6A) {
> @@ -982,6 +1006,8 @@ static int flv_write_packet(AVFormatContext *s,
> AVPacket *pkt)
>          else if (par->codec_id == AV_CODEC_ID_H264 || par->codec_id ==
> AV_CODEC_ID_MPEG4) {
>              avio_w8(pb, 1); // AVC NALU
>              avio_wb24(pb, pkt->pts - pkt->dts);
> +        } else if (par->codec_id == AV_CODEC_ID_HEVC) {
> +            avio_wb24(pb, pkt->pts - pkt->dts);
>          }
>
>          avio_write(pb, data ? data : pkt->data, size);
> --
> 2.40.0
>
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