Hello,
a week ago I was asking the following question about MPEG4 aspect ratio.
I don't like the idea that avimerge, when adding a second audio
track, deletes some information that was in the original AVI file.
However, I did not have any answer to my e-mail.
Am I the only one that want to use all the features of MPEG4 ?
Are the transcode developers too overloaded to look at this part of
the code ?
Best regards,
Louis
Hello,
when I encode the (french) DVDs of Lords of the RIngs, I use the
following commands
$ mencoder -channels 6 -oac copy -alang fr -ovc xvid -xvidencopts \
bitrate=1700:chroma_opt:vhq=3:bvhq=1:pass=1 \
-passlogfile LotR2-$disk.stats -o LotR2-$disk-fr.avi \
dvd:// -dvd-device /Volumes/LOTR_TWO_TOWERS_SEE_$disk/ \
-vobsubout LotR2-$disk-en -vobsuboutindex 0 -sid 0
$ mencoder -channels 6 -oac copy -alang en -ovc xvid -xvidencopts \
bitrate=1700:chroma_opt:vhq=3:bvhq=1:pass=2 \
-passlogfile LotR2-$disk.stats -o LotR2-$disk-en.avi \
dvd:// -dvd-device /Volumes/LOTR_TWO_TOWERS_SEE_$disk/ \
-vobsubout LotR2-$disk-fr-comment -vobsuboutindex 0 -sid 1
The resulting files are mainly LotR2-$disk-en.avi and LotR2-$disk-
fr.avi which contain
- a video track, using codec XVID and an explicit aspect ratio
- an audio track, using codec AC3
The problem arises from the fact that MPEG4 can specifiy an aspect
ratio (while AVI cannot).
See for example http://www.mplayerhq.hu/DOCS/HTML/en/aspect.html
(currently only available through http://web.archive.org/web/
20041115010423/http://www.mplayerhq.hu/DOCS/HTML/en/aspect.html)
When played with mplayer, the aspect ratio is auto-detected.
However, transcode does not seem to be aware of this feature of MPEG4.
Therefore, when I want to build a single AVI file with two audio
tracks, using
$ avimerge -o LotR2-$disk.avi -i LotR2-$disk-en.avi -p LotR2-$disk-
fr.avi
the information about MPEG4 aspect ratio is not kept.
Here is an example of output of mplayer (I am using MacOSX, but
this should be an architecture independent issue)
$ mplayer LotR3-D1-en.avi
MPlayer dev-CVS-051126-18:35-3.3 (C) 2000-2005 MPlayer Team
Mac OSX static build for ffmpegX
AltiVec found
CPU: PowerPC
Playing LotR3-D1-en.avi.
AVI file format detected.
AVI: ODML: Building odml index (2 superindexchunks)
VIDEO: [XVID] 720x576 12bpp 25.000 fps 1494.6 kbps (182.4
kbyte/s)
Clip info:
Software: MEncoder dev-CVS-051126-18:35-3.3
======================================================================
====
Opening audio decoder: [liba52] AC3 decoding with liba52
Using AltiVec optimized IMDCT transform
AC3: 5.1 (3f+2r+lfe) 48000 Hz 448.0 kbit/s
Checking for AltiVec resampler : 0x0000000a, 2
Using AltiVec optimized resampler
AUDIO: 48000 Hz, 2 ch, s16be, 448.0 kbit/29.17% (ratio: 56000->192000)
Selected audio codec: [a52] afm: liba52 (AC3-liba52)
======================================================================
====
======================================================================
====
Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
Selected video codec: [ffodivx] vfm: ffmpeg (FFmpeg MPEG-4)
======================================================================
====
Building audio filter chain for 48000Hz/2ch/s16be -> 0Hz/0ch/s8...
AO: [macosx] 48000Hz 2ch s16be (2 bytes per sample)
Building audio filter chain for 48000Hz/2ch/s16be -> 48000Hz/2ch/
s16be...
Starting playback...
VDec: vo config request - 720 x 576 (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: [quartz] 720x576 => 1024x576 Planar YV12
$ mplayer LotR3-D1.avi
MPlayer dev-CVS-051126-18:35-3.3 (C) 2000-2005 MPlayer Team
Mac OSX static build for ffmpegX
AltiVec found
CPU: PowerPC
Playing LotR3-D1.avi.
AVI file format detected.
AVI: ODML: Building odml index (3 superindexchunks)
VIDEO: [XVID] 720x576 24bpp 25.000 fps 1494.6 kbps (182.4
kbyte/s)
Clip info:
Software: transcode-1.0.2
======================================================================
====
Opening audio decoder: [liba52] AC3 decoding with liba52
Using AltiVec optimized IMDCT transform
AC3: 5.1 (3f+2r+lfe) 48000 Hz 448.0 kbit/s
Checking for AltiVec resampler : 0x0000000a, 2
Using AltiVec optimized resampler
AUDIO: 48000 Hz, 2 ch, s16be, 448.0 kbit/29.17% (ratio: 56000->192000)
Selected audio codec: [a52] afm: liba52 (AC3-liba52)
======================================================================
====
======================================================================
====
Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
Selected video codec: [ffodivx] vfm: ffmpeg (FFmpeg MPEG-4)
======================================================================
====
Building audio filter chain for 48000Hz/2ch/s16be -> 0Hz/0ch/s8...
AO: [macosx] 48000Hz 2ch s16be (2 bytes per sample)
Building audio filter chain for 48000Hz/2ch/s16be -> 48000Hz/2ch/
s16be...
Starting playback...
VDec: vo config request - 720 x 576 (preferred colorspace: Planar
YV12)
VDec: using Planar YV12 as output csp (no 0)
Movie-Aspect is 1.25:1 - prescaling to correct movie aspect.
VO: [quartz] 720x576 => 720x576 Planar YV12
