[MEncoder-users] transcoding from variable framerate MP4 to avi, a/v sync problem - video stream much shorter

[SilentShade]

Hello everybody.
I'm trying make an all-in-one transcoder for any types of video, for web streaming. The output is AVC/AAC in MP4 container. For that i use the following techique:
1. Encode input to avc/aac and remux it to avi container. (mencoder)
2. Demux audio and video steams into separate files
3. Mux to mp4 with gpac MP4Box

I ran into problem with an input mp4 file having variable framerate.
The sample command for stage 1 is:
mencoder -af volnorm=2 -oac faac -faacopts br=98:mpeg=4:object=2 -channels 2 -srate 44100 -ovc x264 -x264encopts bitrate=500:subq=5:frameref=6:cabac:threads=auto:bframes=3:b_pyramid=normal:weight_b -ofps 30000/1001 -vf pp=hb/vb/lb,dsize=960:720:0,scale=-8:-8,harddup infile.mp4 -o tmp.avi

The input file is about 10 minutes long and has more then 4500 frames. Mencoder continues up to ~780-th frame, and then tells:

Too many audio packets in the buffer: (4096 in 1067205 bytes).
Maybe you are playing a non-interleaved stream/file or the codec failed?
For AVI files, try to force non-interleaved mode with the -ni option.

The result file is 28 seconds long, and a video stream is fast forward.. Audio stream is at normal speed.
I had similar problem with encodinf VBR vmw files, and it was solved by adding source max frame rate with -ofps option. However this doesn't work with mp4 source.
Any help would be much appreciated.
Thanks.

Input file mediainfo:

Format                           : MPEG-4
Format profile                   : Base Media / Version 2
Codec ID                         : mp42
File size                        : 21.0 MiB
Duration                         : 11mn 4s
Overall bit rate                 : 265 Kbps
Encoded date                     : UTC 2011-05-23 07:40:27
Tagged date                      : UTC 2011-05-23 07:41:00
Writing application              : HandBrake 0.9.5 2011010300

Video
ID                               : 1
Format                           : AVC
Format/Info                      : Advanced Video Codec
Format profile                   : High at L3.1
Format settings, CABAC           : Yes
Format settings, ReFrames        : 4 frames
Codec ID                         : avc1
Codec ID/Info                    : Advanced Video Coding
Duration                         : 11mn 4s
Bit rate mode                    : Variable
Bit rate                         : 164 Kbps
Nominal bit rate                 : 300 Kbps
Width                            : 960 pixels
Height                           : 600 pixels
Display aspect ratio             : 1.600
Frame rate mode                  : Variable
Frame rate                       : 6.802 fps
Minimum frame rate               : 0.595 fps
Maximum frame rate               : 29.970 fps
Color space                      : YUV
Chroma subsampling               : 4:2:0
Bit depth                        : 8 bits
Scan type                        : Progressive
Bits/(Pixel*Frame)               : 0.042
Stream size                      : 13.0 MiB (62%)
Writing library                  : x264 core 112
Encoding settings                : cabac=1 / ref=3 / deblock=1:0:0 / analyse=0x3:0x113 / me=hex / subme=7 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=12 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=2 / b_bias=0 / direct=1 / weightb=1 / open_gop=0 / weightp=2 / keyint=70 / keyint_min=6 / scenecut=40 / intra_refresh=0 / rc_lookahead=50 / rc=abr / mbtree=1 / bitrate=300 / ratetol=1.0 / qcomp=0.60 / qpmin=3 / qpmax=51 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00
Encoded date                     : UTC 2011-05-23 07:40:27
Tagged date                      : UTC 2011-05-23 07:41:00
Color primaries                  : BT.601-6 525, BT.1358 525, BT.1700 NTSC, SMPTE 170M
Transfer characteristics         : BT.709-5, BT.1361
Matrix coefficients              : BT.601-6 525, BT.1358 525, BT.1700 NTSC, SMPTE 170M

Audio
ID                               : 2
Format                           : AAC
Format/Info                      : Advanced Audio Codec
Format profile                   : LC
Codec ID                         : 40
Duration                         : 11mn 4s
Bit rate mode                    : Variable
Bit rate                         : 98.6 Kbps
Maximum bit rate                 : 128 Kbps
Channel(s)                       : 1 channel
Channel positions                : Front: C
Sampling rate                    : 48.0 KHz
Compression mode                 : Lossy
Stream size                      : 7.81 MiB (37%)
Language                         : English
Encoded date                     : UTC 2011-05-23 07:40:27
Tagged date                      : UTC 2011-05-23 07:41:00


Output mediainfo:

Format                           : AVI
Format/Info                      : Audio Video Interleave
File size                        : 915 KiB
Duration                         : 26s 378ms
Overall bit rate                 : 284 Kbps
Writing application              : MEncoder SVN-r32726-4.4.3
Writing library                  : MPlayer

Video
ID                               : 0
Format                           : AVC
Format/Info                      : Advanced Video Codec
Format profile                   : High at L3.1
Format settings, CABAC           : Yes
Format settings, ReFrames        : 6 frames
Codec ID                         : h264
Duration                         : 25s 859ms
Bit rate                         : 174 Kbps
Nominal bit rate                 : 164 Kbps
Width                            : 960 pixels
Height                           : 608 pixels
Display aspect ratio             : 1.599
Frame rate                       : 29.970 fps
Color space                      : YUV
Chroma subsampling               : 4:2:0
Bit depth                        : 8 bits
Scan type                        : Progressive
Bits/(Pixel*Frame)               : 0.010
Stream size                      : 550 KiB (60%)
Writing library                  : x264 core 110 r1820 fdcf2ae
Encoding settings                : cabac=1 / ref=6 / deblock=1:0:0 / analyse=0x3:0x113 / me=hex / subme=5 / psy=1 / psy_rd=0.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=0 / threads=6 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=1 / b_bias=0 / direct=1 / weightb=1 / open_gop=0 / weightp=2 / keyint=250 / keyint_min=25 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=abr / mbtree=1 / bitrate=164 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=51 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00

Audio
ID                               : 1
Format                           : 706D
Codec ID                         : 706D
Duration                         : 26s 378ms
Bit rate                         : 98.1 Kbps
Channel(s)                       : 1 channel
Sampling rate                    : 44.1 KHz
Stream size                      : 316 KiB (35%)
Interleave, duration             : 23 ms (0.68 video frame)
Interleave, preload duration     : 2107 ms