[FFmpeg-trac] #7287(avcodec:new): Audiotoolbox decodes 24-bit ALAC as 16-bit

[FFmpeg]

#7287: Audiotoolbox decodes 24-bit ALAC as 16-bit
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             Reporter:  macdavis      |                    Owner:
                 Type:  defect        |                   Status:  new
             Priority:  normal        |                Component:  avcodec
              Version:  git-master    |               Resolution:
             Keywords:  Audiotoolbox  |               Blocked By:
             Blocking:                |  Reproduced by developer:  0
Analyzed by developer:  0             |
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Comment (by bpa):

 The problem starts with the input file.  The "alac" atom says the file has
 16 bit samples (i.e. SampleSize field).  I have just found this exact bug
 in ffmpeg when creating 24 bit ALAC file and was about to file a report.
 Was Untitledsample_24_bit_alac.m4a created by ffmpeg ?

 Selected output from mp4file.
     "Untitledsample_24_bit_alac.m4a": type stbl (moov.trak.mdia.minf.stbl)
       "Untitledsample_24_bit_alac.m4a": type stsd
 (moov.trak.mdia.minf.stbl.stsd)
        "Untitledsample_24_bit_alac.m4a": version = 0 (0x00)
        "Untitledsample_24_bit_alac.m4a": flags = 0 (0x000000)
        "Untitledsample_24_bit_alac.m4a": entryCount = 1 (0x00000001)
        "Untitledsample_24_bit_alac.m4a": type alac
 (moov.trak.mdia.minf.stbl.stsd.alac)
         "Untitledsample_24_bit_alac.m4a": reserved1 = <6 bytes>  00 00 00
 00 00 00  |......|
         "Untitledsample_24_bit_alac.m4a": dataReferenceIndex = 1 (0x0001)
         "Untitledsample_24_bit_alac.m4a": soundVersion = 0 (0x0000)
         "Untitledsample_24_bit_alac.m4a": reserved2 = <6 bytes>  00 00 00
 00 00 00  |......|
         "Untitledsample_24_bit_alac.m4a": channels = 2 (0x0002)
         "Untitledsample_24_bit_alac.m4a": sampleSize = 16 (0x0010)
         "Untitledsample_24_bit_alac.m4a": compressionId = 0 (0x0000)
         "Untitledsample_24_bit_alac.m4a": packetSize = 0 (0x0000)
         "Untitledsample_24_bit_alac.m4a": timeScale = 2890137600
 (0xac440000)
         "Untitledsample_24_bit_alac.m4a": type alac
 (moov.trak.mdia.minf.stbl.stsd.alac.alac)
          "Untitledsample_24_bit_alac.m4a": decoderConfig = <28 bytes>

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Ticket URL: <https://trac.ffmpeg.org/ticket/7287#comment:1>
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