IPCM Not detected as pcm_s24be and decoded accordingly by FFMpeg

[Francesco Bucciantini]

Summary of the bug:

IPCM audio files muxed in MP4 are not correctly detected as pcm_s24be and decoded accordingly.

How to reproduce:

ffmpeg.exe -i %1 -acodec pcm_s24le -ar 48000 -ac 2 -y out1.wav

Expected behavior: decode IPCM and encode a PCM signed 24-bit little-endian file muxed in .wav

Actual behavior: Error - Decoder (codec none) not found for input stream #0:1

Full log:

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Z:\IPCM_Sample.MP4':
  Metadata:
    major_brand     : XAVC
    minor_version   : 17440767
    compatible_brands: XAVCmp42iso2
    creation_time   : 2021-05-04T04:54:00.000000Z
  Duration: 00:00:10.08, start: 0.000000, bitrate: 80002 kb/s
    Stream #0:0(und): Video: h264 (High 4:2:2) (avc1 / 0x31637661), yuv422p10le(pc), 1920x1080 [SAR 1:1 DAR 16:9], 46772 kb/s, 50 fps, 50 tbr, 50k tbn, 100 tbc (default)
    Metadata:
      creation_time   : 2021-05-04T04:54:00.000000Z
      handler_name    : Video Media Handler
      vendor_id       : [0][0][0][0]
      encoder         : AVC Coding
    Stream #0:1(und): Audio: none (ipcm / 0x6D637069), 48000 Hz, stereo (default)
    Metadata:
      creation_time   : 2021-05-04T04:54:00.000000Z
      handler_name    : Sound Media Handler
      vendor_id       : [0][0][0][0]
    Stream #0:2(und): Data: none (rtmd / 0x646D7472), 4505 kb/s (default)
    Metadata:
      creation_time   : 2021-05-04T04:54:00.000000Z
      handler_name    : Timed Metadata Media Handler
      timecode        : 01:24:55:10
Stream mapping:
  Stream #0:1 -> #0:0 (? (?) -> pcm_s24le (native))
Decoder (codec none) not found for input stream #0:1

ffmpeg version N-100846-g488e65037b
built on 27/01/2021 01:53 AM UTC+01:00

same behavior occurs on:
ffmpeg version 2021-05-05-git-7c451b609c
built on 05/05/2021 12:29 PM UTC+01:00

Actual workaround: manually setting the decoder to pcm_s24be PCM signed 24-bit big-endian makes it possible to decode the file correctly.

This:

ffmpeg.exe -c:a pcm_s24be -i %1 -acodec pcm_s24le -ar 48000 -ac 2 -y out1.wav

works just fine:

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Z:\IPCM_Sample.MP4':
  Metadata:
    major_brand     : XAVC
    minor_version   : 17440767
    compatible_brands: XAVCmp42iso2
    creation_time   : 2021-05-04T04:54:00.000000Z
  Duration: 00:00:10.08, start: 0.000000, bitrate: 80002 kb/s
    Stream #0:0(und): Video: h264 (High 4:2:2) (avc1 / 0x31637661), yuv422p10le(pc), 1920x1080 [SAR 1:1 DAR 16:9], 46772 kb/s, 50 fps, 50 tbr, 50k tbn, 100 tbc (default)
    Metadata:
      creation_time   : 2021-05-04T04:54:00.000000Z
      handler_name    : Video Media Handler
      vendor_id       : [0][0][0][0]
      encoder         : AVC Coding
    Stream #0:1(und): Audio: pcm_s24be (ipcm / 0x6D637069), 48000 Hz, stereo, s32 (24 bit), 2304 kb/s (default)
    Metadata:
      creation_time   : 2021-05-04T04:54:00.000000Z
      handler_name    : Sound Media Handler
      vendor_id       : [0][0][0][0]
    Stream #0:2(und): Data: none (rtmd / 0x646D7472), 4505 kb/s (default)
    Metadata:
      creation_time   : 2021-05-04T04:54:00.000000Z
      handler_name    : Timed Metadata Media Handler
      timecode        : 01:24:55:10
Stream mapping:
  Stream #0:1 -> #0:0 (pcm_s24be (native) -> pcm_s24le (native))
Press [q] to stop, [?] for help
Output #0, wav, to 'out1.wav':
  Metadata:
    major_brand     : XAVC
    minor_version   : 17440767
    compatible_brands: XAVCmp42iso2
    ISFT            : Lavf58.65.101
    Stream #0:0(und): Audio: pcm_s24le ([1][0][0][0] / 0x0001), 48000 Hz, stereo, s32 (24 bit), 2304 kb/s (default)
    Metadata:
      creation_time   : 2021-05-04T04:54:00.000000Z
      handler_name    : Sound Media Handler
      vendor_id       : [0][0][0][0]
      encoder         : Lavc58.119.100 pcm_s24le
size=    2835kB time=00:00:10.06 bitrate=2306.5kbits/s speed= 196x
video:0kB audio:2835kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.003514%

[Francesco Bucciantini]

IPCM Sample: ​https://we.tl/t-UkEK5c94if

Decoded and re-encoded to PCM 24bit little endian audio: ​https://we.tl/t-4yTKInyzmt

[Francesco Bucciantini]

MediaInfo: