[FFmpeg-user] Creating MP4 with G711 audio

[Paul B Mahol]

ffmpeg can not mux pcm_alaw/pcm_mulaw into MP4.

On Thu, Nov 21, 2024 at 10:41 AM d.gordenin at ngslab.ru <d.gordenin at ngslab.ru>
wrote:

> Hello.
>
> I'm trying to make a mp4 file from a video/audio stream. When audio is
> AAC it works fine. But I cannot pack G711U audio.
>
> |av_register_all(); avcodec_register_all();
> av_log_set_callback(nullptr); av_format_context_ =
> avformat_alloc_context(); if (!av_format_context_) { std::string
> error_msg = "Failed to allocate avformat context";
> log_->Error(error_msg); throw std::runtime_error(error_msg.c_str()); }
> av_format_context_->oformat = av_guess_format("mp4", filename.c_str(),
> NULL); strcpy(av_format_context_->filename, filename.c_str()); AVCodec*
> codec = avcodec_find_encoder(AV_CODEC_ID_PCM_MULAW);
> av_format_context_->oformat->audio_codec = codec->id; audio_stream_ =
> avformat_new_stream(av_format_context_, codec); if (audio_stream_ ==
> nullptr) { log_->Error("Can not create audiostream."); return false; }
> AVCodecContext& codec_context = *audio_stream_->codec; if
> (avcodec_copy_context(audio_stream_->codec,
> av_format_context_->streams[1]->codec) != 0) { log_->Error("Failed to
> Copy Context"); return false; } audio_stream_->time_base = { 1,
> codec_context.sample_rate }; if (av_format_context_->oformat->flags &
> AVFMT_GLOBALHEADER) codec_context.flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
> log_->Info("Init output {}", filename);
> av_dump_format(av_format_context_, 0, filename.c_str(), 1); int ret =
> avio_open(&av_format_context_->pb, filename.c_str(), AVIO_FLAG_WRITE);
> if (ret < 0) { log_->Error("Can not open file for writing."); return
> false; } ret = avformat_write_header(av_format_context_, NULL); if (ret
> < 0) { log_->Error("Can not write header."); return false; } |
>
> Here avformat_write_header() returns -22. What's wrong here? Which data
> should I supply to this function?
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