When I play 5.1 ac3 audio, the audio channels are mixed up. Initially, the Center/LFE is swapped with the rear surround, however seeking during playback can rotate the outputs. I've uploaded a sample to ftp://mplayerhq.hu/MPlayer/incoming/6.1_test.avi. Play it, and seek back a few times at the beginning to see the soud output moving between speekers. This happens with mplayer-0.90rc5 as well as with the current CVS. I use alsa-0.9.2, and it happens both with -ao alsa9 and with -ao oss (using alsa oss emulation). My motherboard is the Asus A7N8X deluxe, and I'm using the integrated nForce2 audio. The mplayer -v output is included below. Zoli Using GNU internationalization Original domain: messages Original dirname: /usr/share/locale Current domain: mplayer Current dirname: /usr/share/locale MPlayer dev-CVS-030515-00:28-3.3 (C) 2000-2003 Arpad Gereoffy (see DOCS) CPU: Advanced Micro Devices (Family: 6, Stepping: 1) Detected cache-line size is 64 bytes CPUflags: MMX: 1 MMX2: 1 3DNow: 1 3DNow2: 1 SSE: 1 SSE2: 0 Compiled for x86 CPU with extensions: MMX MMX2 3DNow 3DNowEx SSE Reading config file /etc/mplayer/mplayer.conf Reading config file /home/hzoli/.mplayer/config Reading /home/hzoli/.mplayer/codecs.conf: Reading /etc/mplayer/codecs.conf: 55 audio & 144 video codecs CommandLine: '-v' '-ao' 'alsa9' '6.1_test.avi' '-channels' '6' get_path('font/font.desc') -> '/home/hzoli/.mplayer/font/font.desc' font: can't open file: /home/hzoli/.mplayer/font/font.desc Font /usr/share/mplayer/font/font.desc loaded successfully! (206 chars) Using MMX (with tiny bit MMX2) Optimized OnScreenDisplay Using Linux hardware RTC timing (1024Hz). get_path('input.conf') -> '/home/hzoli/.mplayer/input.conf' Parsing input config file /etc/mplayer/input.conf Input config file /etc/mplayer/input.conf parsed : 52 binds Setting up LIRC support... get_path('6.1_test.avi.conf') -> '/home/hzoli/.mplayer/6.1_test.avi.conf' Playing 6.1_test.avi Not an URL! [file] File size is 5691242 bytes STREAM: [file] 6.1_test.avi STREAM: Description: File STREAM: Author: Albeu STREAM: Comment: based on the code from ??? (probably Arpi) AVI file format detected. list_end=0x13A ======= AVI Header ======= us/frame: 33366 (fps=29.971) max bytes/sec: 0 padding: 0 MainAVIHeader.dwFlags: (2320) HAS_INDEX IS_INTERLEAVED TRUST_CKTYPE frames total: 2094 initial: 0 streams: 2 Suggested BufferSize: 0 Size: 720 x 480 list_end=0xD4 ==> Found video stream: 0 ======= STREAM Header ======= Type: vids FCC: (0) Flags: 0 Priority: 0 Language: 0 InitialFrames: 0 Rate: 299699/10000 = 29.970 Start: 0 Len: 2094 Suggested BufferSize: 83829 Quality 0 Sample size: 0 found 'bih', 40 bytes of 40 ======= VIDEO Format ====== biSize 40 biWidth 720 biHeight 480 biPlanes 1 biBitCount 24 biCompression 1482049860='DIVX' biSizeImage 1036800 =========================== Regenerating keyframe table for DIVX 4 video list_end=0x13A ==> Found audio stream: 1 ======= STREAM Header ======= Type: auds FCC: (0) Flags: 0 Priority: 0 Language: 0 InitialFrames: 0 Rate: 56000/1 = 56000.000 Start: 0 Len: 3913728 Suggested BufferSize: 28000 Quality 0 Sample size: 1 found 'wf', 18 bytes of 18 ======= WAVE Format ======= Format Tag: 8192 (0x2000) Channels: 2 Samplerate: 48000 avg byte/sec: 56000 Block align: 1 bits/sample: 16 cbSize: 0 list_end=0x166 hdr=Software size=24 Software : MEncoder 0.90rc5-3.2.3 Broken chunk? chunksize=1682 (id=JUNK) list_end=0x564BC2 Found movie at 0x80C - 0x564BC2 Reading INDEX block, 2234 chunks for 2094 frames (fpos=0x564bca) AVI index offset: 0x808 (movi=0x80C idx0=0x4 idx1=0x6D6C) Auto-selected AVI audio ID = 1 Auto-selected AVI video ID = 0 AVI: Searching for audio stream (id:1) AVI video size=1720725 (2094) audio size=3913728 (3913728) VIDEO: [DIVX] 720x480 24bpp 29.97 fps 197.0 kbps (24.0 kbyte/s) [V] filefmt:3 fourcc:0x58564944 size:720x480 fps:29.97 ftime:=0.0334 Clip info: Software: MEncoder 0.90rc5-3.2.3 get_path('sub/') -> '/home/hzoli/.mplayer/sub/' get_path('default.sub') -> '/home/hzoli/.mplayer/default.sub' ========================================================================== Opening audio decoder: [liba52] AC3 decoding with liba52 dec_audio: Allocating 3840 bytes for input buffer dec_audio: Allocating 18432 + 65536 = 83968 bytes for output buffer AC3: 5.1 (3f+2r+lfe) 48000 Hz 448.0 kbit/s A52 flags before a52_frame: 0x37 A52 flags after a52_frame: 0x17 AUDIO: 48000 Hz, 6 ch, 16 bit (0x10), ratio: 56000->576000 (448.0 kbit) Selected audio codec: [a52] afm:liba52 (AC3-liba52) ========================================================================== X11 opening display: :0.0 vo: X11 color mask: FFFFFF (R:FF0000 G:FF00 B:FF) vo: X11 running at 1600x1200 with depth 24 and 32 bpp (":0.0" => local display) [x11] Unknown wm type... ========================================================================== Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family INFO: libavcodec init OK! Selected video codec: [ffodivx] vfm:ffmpeg (FFmpeg MPEG-4) ========================================================================== Checking audio filter chain for 48000Hz/6ch/16bit -> 48000Hz/6ch/16bit... [libaf] Adding filter dummy [dummy] Was reinitialized, rate=48000Hz, nch = 6, format = 0x00000001 and bps = 2 AF_pre: af format: 2 bps, 6 ch, 48000 hz, little endian signed int AF_pre: 48000Hz 6ch Signed 16-bit (Little-Endian) alsa-init: testing and bugreports are welcome. alsa-init: requested format: 48000 Hz, 6 channels, Signed 16-bit (Little-Endian) alsa-init: compiled for ALSA-0.9.2 alsa-init: got device=0, subdevice=0 alsa-init: 1 soundcard found, using: hw:0,0 alsa-init: pcm opend in block-mode alsa-init: chunksize set to 1024 alsa-init: current val=5, fragcount=5 alsa-init: got buffersize=61440 alsa9: 48000 Hz/6 channels/12 bpf/61440 bytes buffer/Signed 16 bit Little Endian AO: [alsa9] 48000Hz 6ch Signed 16-bit (Little-Endian) (2 bps) AO: Description: ALSA-0.9.x audio output AO: Author: Alex Beregszaszi <alex@naxine.org>, Joy Winter <joy@pingfm.org> AO: Comment: under developement Building audio filter chain for 48000Hz/6ch/16bit -> 48000Hz/6ch/16bit... [dummy] Was reinitialized, rate=48000Hz, nch = 6, format = 0x00000001 and bps = 2 [dummy] Was reinitialized, rate=48000Hz, nch = 6, format = 0x00000001 and bps = 2 Starting playback... alsa-space: free space = 61440, status=140691288, prepared -- This file was encoded with libavcodec build 4655 [ffmpeg] aspect_ratio: 1.333333 VDec: vo config request - 720 x 480 (preferred csp: Planar YV12) Trying filter chain: vo VDec: using Planar YV12 as output csp (no 0) Movie-Aspect is 1.33:1 - prescaling to correct movie aspect. VO Config (720x480->720x540,flags=0,'MPlayer',0x32315659) VO: [xv] 720x480 => 720x540 Planar YV12 VO: Description: X11/Xv VO: Author: Gerd Knorr <kraxel@goldbach.in-berlin.de> and others Xvideo image format: 0x32595559 (YUY2) packed Xvideo image format: 0x32315659 (YV12) planar Xvideo image format: 0x59565955 (UYVY) packed Xvideo image format: 0x30323449 (I420) planar using Xvideo port 137 for hw scaling [xv] dx: 0 dy: 0 dw: 720 dh: 540 *** [vo] Allocating (slices) mp_image_t, 720x480x12bpp YUV planar, 518400 bytes [xv] dx: 0 dy: 0 dw: 720 dh: 540 A: 0.0 V: 0.0 A-V: 0.015 ct: 0.000 1/ 1 0% 0% 0.0% 0 0 0% XXX initial v_pts=0.000 a_pos=28000 (0.500) *** [vo] Allocating (slices) mp_image_t, 720x480x12bpp YUV planar, 518400 bytes Uninit audio filters... [libaf] Removing filter dummy uninit audio: liba52 uninit video: ffmpeg DEMUXER: freeing demuxer at 0x855a618 alsa-uninit: pcm closed vo: uninit ... Exiting... (Quit)