[MPlayer-users] AAC LC 5.1 audio not recognized by mplayer

[Ulion]

2008/5/3 Justin Randall <jrrandall at gmail.com>:
> Hi all,
>
>  I can't seem to get mplayer to give me 6 channel audio playback on my
>  AAC encodes.  Here are the steps I take and some debug info...
>
>  I converted a valid AC3 5.1 surround audio file to a 6 channel wave using:
>  > mplayer $infile -af channels=6:6:0:0:1:1:2:4:3:5:4:2:5:3 -ao pcm:fast: -channels 6 -novideo
>  and then I converted that 6 channel wave to AAC LC 5.1 using nero
>  > neroAacEnc -ignorelength -q 0.38 -if $wav_file -of $aac_file
>  but the resulting supposed 5.1 channel audio file is not recognized by
>  mplayer.  It says that FAAD cannot find the compressed input bitrate
>  of the aac stream.  I'm asking because while mplayer falls back to two
>  channels for audio, both my PS3 and QuickTime (if you believe it)
>  recognize the audio as 5.1.  I can confirm that the PS3 does in fact
>  put out all 6 channels over my surround system.  I can only confirm
>  that QuickTime recognizes the stream in it's info settings since I
>  don't have surround set up on my PC (maybe that is why mplayer
>  defaults to stereo?).
>
>  Here is the printout of mplayer:
>
>  >>mplayer test.mp4
>  MPlayer Sherpya-SVN-r26446-4.2.3 (C) 2000-2008 MPlayer Team
>  CPU: AMD Athlon(tm) 64 X2 Dual Core Processor 4200+ (Family: 15, Model: 43, Step
>  ping: 1)
>  CPUflags:  MMX: 1 MMX2: 1 3DNow: 1 3DNow2: 1 SSE: 1 SSE2: 1
>  Compiled with runtime CPU detection.
>
>  Playing test.mp4.
>  libavformat file format detected.
>  [lavf] Video stream found, -vid 0
>  [lavf] Audio stream found, -aid 1
>  VIDEO:  [avc1]  1280x720  24bpp  23.976 fps    0.0 kbps ( 0.0 kbyte/s)
>  ==========================================================================
>  Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
>  Selected video codec: [ffh264] vfm: ffmpeg (FFmpeg H.264)
>  ==========================================================================
>  ==========================================================================
>  Opening audio decoder: [faad] AAC (MPEG2/4 Advanced Audio Coding)
>  FAAD: compressed input bitrate missing, assuming 128kbit/s!
>  AUDIO: 48000 Hz, 2 ch, s16le, 128.0 kbit/8.33% (ratio: 16000->192000)
>  Selected audio codec: [faad] afm: faad (FAAD AAC (MPEG-2/MPEG-4 Audio) decoder)
>  ==========================================================================
>  AO: [dsound] 48000Hz 2ch s16le (2 bytes per sample)
>  Starting playback...
>  VDec: vo config request - 1280 x 720 (preferred colorspace: Planar YV12)
>  VDec: using Planar YV12 as output csp (no 0)
>  Movie-Aspect is 1.78:1 - prescaling to correct movie aspect.
>  VO: [directx] 1280x720 => 1280x720 Planar YV12
>
>
>  The output of mp4box -info for the same file results in the audio
>  stream being reported correctly as 6 channels on track 2.
>
>  >>mp4box -info test.mp4
>  * Movie Info *
>         Timescale 600 - Duration 00:21:17.161
>         Fragmented File no - 2 track(s)
>         File Brand isom - version 1
>         Created: GMT Sat May 03 04:53:57 2008
>
>  File has root IOD
>  Scene PL 0xff - Graphics PL 0xff - OD PL 0xff
>  Visual PL: AVC/H264 Profile (0x15)
>  Audio PL: AAC Profile @ Level 4 (0x2a)
>  No streams included in root OD
>
>  Track # 1 Info - TrackID 1 - TimeScale 24000 - Duration 00:21:17.067
>  Media Info: Language "English" - Type "vide:avc1" - 30619 samples
>  MPEG-4 Config: Visual Stream - ObjectTypeIndication 0x21
>  AVC/H264 Video - Visual Size 1280 x 720 - Profile High @ Level 4.1
>  NAL Unit length bits: 32
>  Pixel Aspect Ratio 1:1 - Indicated track size 1280 x 720
>  Self-synchronized
>
>  Track # 2 Info - TrackID 2 - TimeScale 48000 - Duration 00:21:17.162
>  Media Info: Language "English" - Type "soun:mp4a" - 59867 samples
>  MPEG-4 Config: Audio Stream - ObjectTypeIndication 0x40
>  MPEG-4 Audio AAC LC - 6 Channel(s) - SampleRate 48000
>  Synchronized on stream 1
>
>
>  Does anybody have any thoughts on this or have you seen this behavior
>  before?  Does mplayer need to have the audio in the first stream to
>  properly detect all channels?  I am fairly confident I did all the
>  right steps, but mplayer refuses to acknowledge 6 channel audio.  Any
>  advice would be appreciated on this problem.

I think mplayer can detected the 6ch, when you add '-v' as parameter
of mplayer, you will see it.
if you want mplayer output 6ch, you have to add '-channels 6' as
mplayer's parameter or add it in mplayer's config file.

-- 
Ulion