Hi all,

I'm having a problem where melt produces a video that plays at half the
speed that it should. I wonder if anyone can help me please? Here's a
testcase:

$ wget http://the.earth.li/~igloo/mlt_problem/result_half_speed.sh
$ wget http://the.earth.li/~igloo/mlt_problem/result_half_speed.mlt
$ wget http://the.earth.li/~igloo/mlt_problem/result_half_speed.mp4
(less than 0.5 MB)
$ sh result_half_speed.sh 
+ melt consumer:result_half_speed.mlt profile=atsc_1080p_50 -consumer 
avformat:result_half_speed.vob progress=1 f=dvd vcodec=mpeg2video acodec=ac3 
b=5000k maxrate=8000k minrate=0 bufsize=1835008 packetsize=2048 
muxrate=10080000 ab=192k ar=48000 s=720x576 g=15 me_range=63 trellis=1 
profile=dv_pal_wide threads=1 real_time=-1
libdc1394 error: Failed to initialize libdc1394
Current Frame:        207, percentage:         99
$

but result_half_speed.mp4 is 4 seconds long, and result_half_speed.vob
is 8 seconds long.

My melt identifies itself as 0.7.3. I built it from git; I believe it's
commit b9c5164f875d110a3c62cdc0b625f070222ca6a5.

This testcase is based on what kdenlive generates, so I don't know if
the bug is in melt, or if kdenlive is generating a bad commandline?


More details:

The input video I believe is 1920x1080 50 frames per second progressive.

If I add "-verbose" to the melt commandline then I get:

[NULL @ 0xa7aa60] [Eval @ 0x7fefec28c560] Undefined constant or missing '(' in 
'dv_pal_wide'
[NULL @ 0xa7aa60] Unable to parse option value "dv_pal_wide"
[NULL @ 0xa78d60] [Eval @ 0x7fefec28c510] Undefined constant or missing '(' in 
'dv_pal_wide'
[NULL @ 0xa78d60] Unable to parse option value "dv_pal_wide"
[ac3_fixed @ 0xa78d60] channel_layout not specified
[ac3_fixed @ 0xa78d60] No channel layout specified. The encoder will guess the 
layout, but it might be incorrect.
[producer avformat] audio: total_streams 1 max_stream 1 total_channels 6 
max_channels 6

Google finds a few hits saying not to worry about those messages, but
they still look suspicious to me!

And here's the ffprobe output for the mp4 and vob:

$ ffprobe result_half_speed.mp4
ffprobe version git-N-30047-g3c7650a, Copyright (c) 2007-2011 the FFmpeg 
developers
  built on May 19 2011 14:24:20 with gcc 4.6.1 20110507 (prerelease)
  configuration: --prefix=/home/ian/code/ffmpeg/inst --enable-gpl 
--enable-version3 --enable-postproc --enable-swscale --enable-x11grab 
--enable-avfilter --enable-vdpau --enable-bzlib --enable-libgsm 
--enable-libschroedinger --enable-libspeex --enable-libtheora 
--enable-libvorbis --enable-pthreads --enable-zlib --enable-libvpx 
--enable-frei0r --enable-shared --enable-nonfree --enable-libdc1394 
--enable-libdirac --enable-libfreetype --enable-libopenjpeg --enable-librtmp 
--enable-libx264
  libavutil    51.  2. 1 / 51.  2. 1
  libavcodec   53.  6. 0 / 53.  6. 0
  libavformat  53.  1. 0 / 53.  1. 0
  libavdevice  53.  0. 0 / 53.  0. 0
  libavfilter   2.  5. 0 /  2.  5. 0
  libswscale    0. 14. 0 /  0. 14. 0
  libpostproc  51.  2. 0 / 51.  2. 0
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'result_half_speed.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    creation_time   : 1970-01-01 00:00:00
    encoder         : Lavf53.1.0
  Duration: 00:00:04.16, start: 0.000000, bitrate: 658 kb/s
    Stream #0.0(und): Video: h264 (Constrained Baseline), yuv420p, 1920x1080 
[PAR 1:1 DAR 16:9], 204 kb/s, 50 fps, 50 tbr, 50 tbn, 100 tbc
    Metadata:
      creation_time   : 1970-01-01 00:00:00
    Stream #0.1(und): Audio: ac3, 48000 Hz, 6 channels, s16, 448 kb/s
    Metadata:
      creation_time   : 1970-01-01 00:00:00

$ ffprobe result_half_speed.vob 
ffprobe version git-N-30047-g3c7650a, Copyright (c) 2007-2011 the FFmpeg 
developers
  built on May 19 2011 14:24:20 with gcc 4.6.1 20110507 (prerelease)
  configuration: --prefix=/home/ian/code/ffmpeg/inst --enable-gpl 
--enable-version3 --enable-postproc --enable-swscale --enable-x11grab 
--enable-avfilter --enable-vdpau --enable-bzlib --enable-libgsm 
--enable-libschroedinger --enable-libspeex --enable-libtheora 
--enable-libvorbis --enable-pthreads --enable-zlib --enable-libvpx 
--enable-frei0r --enable-shared --enable-nonfree --enable-libdc1394 
--enable-libdirac --enable-libfreetype --enable-libopenjpeg --enable-librtmp 
--enable-libx264
  libavutil    51.  2. 1 / 51.  2. 1
  libavcodec   53.  6. 0 / 53.  6. 0
  libavformat  53.  1. 0 / 53.  1. 0
  libavdevice  53.  0. 0 / 53.  0. 0
  libavfilter   2.  5. 0 /  2.  5. 0
  libswscale    0. 14. 0 /  0. 14. 0
  libpostproc  51.  2. 0 / 51.  2. 0
[mpeg @ 0x22a7780] max_analyze_duration 5000000 reached at 5000000
Input #0, mpeg, from 'result_half_speed.vob':
  Duration: 00:00:08.28, start: 1.000000, bitrate: 3005 kb/s
    Stream #0.0[0x1e0]: Video: mpeg2video (Main), yuv420p, 720x576 [PAR 64:45 
DAR 16:9], 8000 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0.1[0x80]: Audio: ac3, 48000 Hz, stereo, s16, 192 kb/s


Please let me know if there is any more information you need from me.


Thanks
Ian


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