[FFmpeg-devel] [PATCH] AAC sequence header data setup if stream copy

Michael Niedermayer michael at niedermayer.cc
Wed Nov 18 18:37:51 CET 2015


On Wed, Nov 18, 2015 at 05:04:06PM +0200, Maksym Veremeyenko wrote:
> Hi,
> 
> FLV remuxed from MPEG-TS stream does not contains *AAC sequence
> header* as result no audio with some RTMP servers like *crtmpserver*
> and YouTube.
> 
> I am not a first who faced with such problem:
> http://lists.ffmpeg.org/pipermail/ffmpeg-devel/2014-May/157791.html
> http://lists.ffmpeg.org/pipermail/ffmpeg-devel/2014-June/158342.html
> 
> Proposed solution differ from *Tudor SUCIU* a bit. It use the same
> idea but implementation was taken from
> *ff_aac_put_audio_specific_config*.
> 
> Attached patch implement setting *AAC sequence header* in two ways.
> First way is just to set given bytes into that header:
> 
> ffmpeg -re -f mpegts -i /usr/local/src/2015-11-15/M1_award.ts
> -acodec copy -vcodec copy -bsf:a aac_adtstoasc -aac_seq_header_data
> "1190" -flags +global_header -f flv rtmp://127.0.0.1/live/demo
> 
> 11 90 is a two bytes of *AAC sequence header* that describe
> AAC/LC+48000Hz+stereo
> 
> another way is just build it from encoder parameters:
> 
> ffmpeg -re -f mpegts -i /usr/local/src/2015-11-15/M1_award.ts
> -acodec copy -vcodec copy -bsf:a aac_adtstoasc -flvflags
> aac_seq_header_detect -flags +global_header -f flv
> rtmp://127.0.0.1/live/demo
> 
> but it require copying *profile* value from decoder context in ffmpeg.c:
> 
> diff --git a/ffmpeg.c b/ffmpeg.c
> index c4e9280..a976f61 100644
> --- a/ffmpeg.c
> +++ b/ffmpeg.c
> @@ -2970,6 +2970,7 @@ static int transcode_init(void)
>                  enc_ctx->audio_service_type = dec_ctx->audio_service_type;
>                  enc_ctx->block_align        = dec_ctx->block_align;
>                  enc_ctx->initial_padding    = dec_ctx->delay;
> +                enc_ctx->profile            = dec_ctx->profile;
>  #if FF_API_AUDIOENC_DELAY
>                  enc_ctx->delay              = dec_ctx->delay;
>  #endif
> 
> both methods makes possible to work with *crtmpserver* and YouTube
> by simple remuxing streams for publishing
> 
> -- 
> Maksym Veremeyenko

>  ffmpeg.c             |    1 
>  libavformat/flvenc.c |   53 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 54 insertions(+)
> ebc7cedea320684411a4a4c7f6a962c939612db0  0001-AAC-sequence-header-data-setup-if-stream-copy.patch
> From afdc10c4f496d1e72a3b955513cf6891767d731a Mon Sep 17 00:00:00 2001
> From: Maksym Veremeyenko <verem at m1.tv>
> Date: Tue, 17 Nov 2015 20:02:22 +0200
> Subject: [PATCH] AAC sequence header data setup if stream copy
> 
> ---
>  ffmpeg.c             |    1 +
>  libavformat/flvenc.c |   53 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 54 insertions(+), 0 deletions(-)
> 
> diff --git a/ffmpeg.c b/ffmpeg.c
> index c4e9280..a976f61 100644
> --- a/ffmpeg.c
> +++ b/ffmpeg.c
> @@ -2970,6 +2970,7 @@ static int transcode_init(void)
>                  enc_ctx->audio_service_type = dec_ctx->audio_service_type;
>                  enc_ctx->block_align        = dec_ctx->block_align;
>                  enc_ctx->initial_padding    = dec_ctx->delay;
> +                enc_ctx->profile            = dec_ctx->profile;
>  #if FF_API_AUDIOENC_DELAY
>                  enc_ctx->delay              = dec_ctx->delay;
>  #endif
> diff --git a/libavformat/flvenc.c b/libavformat/flvenc.c
> index e217ba8..6380fd7 100644
> --- a/libavformat/flvenc.c
> +++ b/libavformat/flvenc.c
> @@ -28,6 +28,9 @@
>  #include "flv.h"
>  #include "internal.h"
>  #include "metadata.h"
> +#include "libavutil/opt.h"
> +#include "libavcodec/put_bits.h"
> +#include "libavcodec/aacenctab.h"
>  
>  
>  static const AVCodecTag flv_video_codec_ids[] = {
> @@ -68,6 +71,10 @@ typedef struct FLVContext {
>      AVCodecContext *video_enc;
>      double framerate;
>      AVCodecContext *data_enc;
> +
> +    uint8_t *aac_seq_header_data;
> +    int aac_seq_header_length;
> +    int flags;
>  } FLVContext;
>  
>  typedef struct FLVStreamContext {
> @@ -452,6 +459,37 @@ static int flv_write_header(AVFormatContext *s)
>              if (enc->codec_id == AV_CODEC_ID_AAC) {
>                  avio_w8(pb, get_audio_flags(s, enc));
>                  avio_w8(pb, 0); // AAC sequence header
> +                if (!enc->extradata_size && flv->aac_seq_header_data)
> +                {
> +                    avio_write(pb, flv->aac_seq_header_data, flv->aac_seq_header_length);
> +
> +                    av_log(s, AV_LOG_WARNING, "AAC sequence header length=%d\n", flv->aac_seq_header_length);
> +                }
> +                else if (!enc->extradata_size && !flv->aac_seq_header_data && flv->flags & 1)
> +                {
> +                    PutBitContext pbc;
> +                    int samplerate_index;
> +                    int channels = flv->audio_enc->channels - (flv->audio_enc->channels == 8 ? 1 : 0);
> +                    uint8_t data[2];
> +
> +                    for (samplerate_index = 0; samplerate_index < 16; samplerate_index++)
> +                        if (flv->audio_enc->sample_rate == mpeg4audio_sample_rates[samplerate_index])
> +                            break;
> +
> +                    init_put_bits(&pbc, data, sizeof(data));
> +                    put_bits(&pbc, 5, flv->audio_enc->profile + 1); //profile
> +                    put_bits(&pbc, 4, samplerate_index); //sample rate index
> +                    put_bits(&pbc, 4, channels);
> +                    put_bits(&pbc, 1, 0); //frame length - 1024 samples
> +                    put_bits(&pbc, 1, 0); //does not depend on core coder
> +                    put_bits(&pbc, 1, 0); //is not extension
> +                    flush_put_bits(&pbc);
> +
> +                    avio_w8(pb, data[0]);
> +                    avio_w8(pb, data[1]);
> +
> +                    av_log(s, AV_LOG_WARNING, "AAC sequence header: %02x %02x.\n", data[0], data[1]);
> +                }
>                  avio_write(pb, enc->extradata, enc->extradata_size);
>              } else {
>                  avio_w8(pb, enc->codec_tag | FLV_FRAME_KEY); // flags
> @@ -655,6 +693,20 @@ static int flv_write_packet(AVFormatContext *s, AVPacket *pkt)
>      return pb->error;
>  }
>  
> +static const AVOption options[] = {
> +    { "flvflags", "FLV muxer flags", offsetof(FLVContext, flags), AV_OPT_TYPE_FLAGS, {.i64 = 0}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "flvflags" },
> +    { "aac_seq_header_detect", "Put AAC sequence header based on stream data", 0, AV_OPT_TYPE_CONST, {.i64 = 1}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "flvflags" },
> +    { "aac_seq_header_data", "Put AAC sequence header data specified", offsetof(FLVContext, aac_seq_header_data), AV_OPT_TYPE_BINARY, {.str = NULL}, .flags = AV_OPT_FLAG_ENCODING_PARAM },
> +    { NULL },
> +};
> +
> +static const AVClass flv_muxer_class = {
> +    .class_name = "flv muxer",
> +    .item_name  = av_default_item_name,
> +    .option     = options,
> +    .version    = LIBAVUTIL_VERSION_INT,
> +};
> +
>  AVOutputFormat ff_flv_muxer = {
>      .name           = "flv",
>      .long_name      = NULL_IF_CONFIG_SMALL("FLV (Flash Video)"),
> @@ -671,4 +723,5 @@ AVOutputFormat ff_flv_muxer = {
>                        },
>      .flags          = AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS |
>                        AVFMT_TS_NONSTRICT,
> +    .priv_class     = &flv_muxer_class,

the first field of the context must be a AVClass

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I know you won't believe me, but the highest form of Human Excellence is
to question oneself and others. -- Socrates
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