Carl

https://www.matroska.org/technical/index.html
https://www.codecguide.com/klcp_ability_comparison.htm - список поддерживаемых кодеков (втч и G.7xx)
https://en.wikipedia.org/wiki/MPEG-4_Part_14
NAudio
Профили данных RTP
RTP audio video profile
GStreamer
- rtpg722depay Extracts G722 audio from RTP packets
SoX

Файл 32.mp3 взят отсюда http://www.kozco.com/tech/soundtests.html

Преобразование:

$ ffmpeg -i 32.mp3 -acodec pcm_alaw -ac 1 -ar 8000 -ab 40000 32.mka
ffmpeg version 3.2.5-1~bpo8+1 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 4.9.2 (Debian 4.9.2-10)
  configuration: --prefix=/usr --extra-version='1~bpo8+1' --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --disable-libebur128 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared
  libavutil      55. 34.101 / 55. 34.101
  libavcodec     57. 64.101 / 57. 64.101
  libavformat    57. 56.101 / 57. 56.101
  libavdevice    57.  1.100 / 57.  1.100
  libavfilter     6. 65.100 /  6. 65.100
  libavresample   3.  1.  0 /  3.  1.  0
  libswscale      4.  2.100 /  4.  2.100
  libswresample   2.  3.100 /  2.  3.100
  libpostproc    54.  1.100 / 54.  1.100
Input #0, mp3, from '32.mp3':
  Duration: 00:00:32.05, start: 0.025057, bitrate: 128 kb/s
    Stream #0:0: Audio: mp3, 44100 Hz, mono, s16p, 128 kb/s
    Metadata:
      encoder         : LAME3.98r
Output #0, matroska, to '32.mka':
  Metadata:
    encoder         : Lavf57.56.101
    Stream #0:0: Audio: pcm_alaw ([6][0][0][0] / 0x0006), 8000 Hz, mono, s16, 64 kb/s
    Metadata:
      encoder         : Lavc57.64.101 pcm_alaw
Stream mapping:
  Stream #0:0 -> #0:0 (mp3 (native) -> pcm_alaw (native))
Press [q] to stop, [?] for help
size=     259kB time=00:00:32.00 bitrate=  66.4kbits/s speed= 790x    
video:0kB audio:250kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 3.681250%

Выдача MediaInfo:

General
Unique ID                                : 17719613707446459289158434415458592130 (0xD54AC6826989681F1A8D31D845F2582)
Complete name                            : C:\zorin\Fedor\CaRL\my-tests\32.mka
Format                                   : Matroska
Format version                           : Version 4 / Version 2
File size                                : 259 KiB
Duration                                 : 32 s 0 ms
Overall bit rate                         : 66.4 kb/s
Writing application                      : Lavf57.56.101
Writing library                          : Lavf57.56.101
ErrorDetectionType                       : Per level 1

Audio
ID                                       : 1
Format                                   : ADPCM
Format profile                           : A-Law
Codec ID                                 : A_MS/ACM / 6
Codec ID/Hint                            : CCITT
Duration                                 : 32 s 0 ms
Bit rate                                 : 64.0 kb/s
Channel(s)                               : 1 channel
Sampling rate                            : 8 000 Hz
Bit depth                                : 8 bits / 8 bits
Stream size                              : 250 KiB (96%)
Writing library                          : Lavc57.64.101 pcm_alaw
Default                                  : Yes
Forced                                   : No

https://toster.ru/q/5442
- Аудиодорожки — VLC, например. Media — Advanced Open File — Show more options.
- В данном случае поможет BSPlayer — в «Audio streams» в окошке «Audio stream selection» указываете какие дорожки видеофайла BSPlayer должен играть одновременно.

в matroska

TrackEntry.CodecID = A_MS/ACM
TrackEntry.CodecPrivate для A_MS/ACM содержит структуру WAVEFORMATEX

Описание структуры WAVEFORMATEX

typedef struct {
  WORD  wFormatTag;
  WORD  nChannels;
  DWORD nSamplesPerSec;
  DWORD nAvgBytesPerSec;
  WORD  nBlockAlign;
  WORD  wBitsPerSample;
  WORD  cbSize;
} WAVEFORMATEX;

wFormatTag - A complete list of format tags can be found in the Mmreg.h header file

#define  WAVE_FORMAT_ALAW                       0x0006 /* Microsoft Corporation */
#define  WAVE_FORMAT_MULAW                      0x0007 /* Microsoft Corporation */
#define  WAVE_FORMAT_G723_ADPCM                 0x0014 /* Antex Electronics Corporation */
#define  WAVE_FORMAT_G721_ADPCM                 0x0040 /* Antex Electronics Corporation */
#define  WAVE_FORMAT_G728_CELP                  0x0041 /* Antex Electronics Corporation */
#define  WAVE_FORMAT_G726_ADPCM                 0x0064 /* APICOM */
#define  WAVE_FORMAT_G722_ADPCM                 0x0065 /* APICOM */
#define  WAVE_FORMAT_G729A                      0x0083 /* AT&T Labs, Inc. */
#define  WAVE_FORMAT_DF_G726                    0x0085 /* DataFusion Systems (Pty) (Ltd) */
#define  WAVE_FORMAT_DF_GSM610                  0x0086 /* DataFusion Systems (Pty) (Ltd) */

https://matroska.org/news/opus_additions.html
https://wiki.xiph.org/MatroskaOpus
- rfc 7845 Ogg Encapsulation for the Opus Audio Codec
http://forum.doom9.org/showthread.php?t=167854 If MKVToolnix can mux Opus into Matroska file now

[Q] Cant play an mkv with opus audio

Audio
ID : 2
Format : Opus
Codec ID : A_OPUS
Duration : 9mn 28s
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 48.0 KHz
Compression mode : Lossy
Title : Track 1
Default : Yes
Forced : No

How to calculate the RTP Timestamp for each packet in an audio stream
- Audio RTP payload formats typically uses an 8Khz clock. Then take the first audio sample containing e.g. 20ms and assign this timestamp t = 0. 20 ms is a 1/50 of a second, hence this equals a 8000/50 = 160 timestamp increment for the following sample. In the case of audio you can calculate the sample duration based on the sample rate, bits per sample, and number of channels. In the case of a live source, the sample might be timestamped already, and you simply have to translate the timestamp to an RTP timestamp.
- A good reference for RTP in general can be found in the Colin Perkins book, RTP - Audio and video for the Internet. While some of the information might be outdated, it will give you a good understanding of RTP.

Типы определены тут: Профили данных RTP

https://github.com/neolynx/tvdaemon/blob/master/lib/Matroska.cpp

  KaxSimpleBlock &simpleblock = AddNewChild<KaxSimpleBlock>( *cluster );
  //KaxSimpleBlock *simpleblock = new KaxSimpleBlock( );
  simpleblock.SetParent( *cluster );
  simpleblock.AddFrame( *track, ts * timecode_scale, *frame, LACING_EBML );
  simpleblock.SetKeyframe( type == DVB_MPEG_ES_FRAME_I );
  simpleblock.SetDiscardable( type == DVB_MPEG_ES_FRAME_B );

  //KaxBlockBlob *blob = new KaxBlockBlob( BLOCK_BLOB_ALWAYS_SIMPLE );
  //blob->SetParent( *cluster );
  //blob->AddFrameAuto( *track, ts * timecode_scale, *frame, LACING_EBML );
  ////blob->SetBlockDuration( 50 * timecode_scale );
  //cluster->AddBlockBlob( blob );

  //cues.AddBlockBlob( simpleblock );
  //WriteSegment( );

Библиотеки