[Bug 28027] New: μ-law rendering with pauses and repetitions

[wine-bugs at winehq.org]

http://bugs.winehq.org/show_bug.cgi?id=28027

           Summary: μ-law rendering with pauses and repetitions
           Product: Wine
           Version: 1.3.26
          Platform: x86
        OS/Version: Mac OS X
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: mmdevapi
        AssignedTo: wine-bugs at winehq.org
        ReportedBy: hoehle at users.sourceforge.net
                CC: aeikum at codeweavers.com


On MacOS, playing the 11kulaw.wav sample from the MCI shell causes intermittent
pauses (of variable duration, roughly ~0.5s). After each pause, sound does not
necessarily resume where it left off, but the audible output is correct (μ-law
was decoded).

MCI shell (bug #20232, comment #10): wine wintest.exe mcishell
open 11kulaw.wav alias u
play u from 0
close u

By contrast, rendering IMA_ADPCM works.  The difference is that ADPCM goes
through Wine's codec, while μ-law is apparently handled by MacOS, as you can
tell from the missing
fixme:g711:G711_StreamSize 
lines that appear on Linux (or in older versions of Wine on MacOS, e.g.
1.1.35).

trace:coreaudio:AudioClient_Initialize (0x11d7b0)->(0, c0000, f4240, c350,
0x139
438, {d7875583-d596-4af9-9c30-7755c50b26f8})
trace:coreaudio:dump_fmt wFormatTag: 0x7 (Unknown)
trace:coreaudio:dump_fmt nChannels: 1
trace:coreaudio:dump_fmt nSamplesPerSec: 11025
trace:coreaudio:dump_fmt nAvgBytesPerSec: 11025
trace:coreaudio:dump_fmt nBlockAlign: 1
trace:coreaudio:dump_fmt wBitsPerSample: 8

One possible fix might be to have mmdevapi refuse all but linear PCM.  Perhaps
this particular bug is nevertheless interesting because it might reveal faults
in the handling of the Mac OS audio units. After all, μ-law might be
transparent to the player because its samples/sec, blockalign etc. look exactly
like linear PCM.

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