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I have strange duration issue when converting videos from mp4 to flv. Also there is a different "start_time", what is that? What does start_time means?

input duration - 0:00:29.577000
input start_time - 0:00:00.000000

output duration - 0:00:51.518000
output start_time - 0:00:21.840000

ffmpeg command:

ffmpeg -y -i 18579-1386758783533.mp4 -c:a libfdk_aac -b:a 128k -ar 22050 -c:v libx264 -pix_fmt yuv420p -s 1920x1080 -framerate 30 v18579-1386758783533.flv

FFprobe - input file:

dead@dead-work-desktop:~/36369/wowzaoutput$ ffprobe 18579-1386758783533.mp4 
ffprobe version git-2013-11-29-0d640c0 Copyright (c) 2007-2013 the FFmpeg developers
  built on Nov 29 2013 11:54:34 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
  configuration: --extra-libs=-ldl --enable-gpl --enable-libass --enable-libfdk-aac --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libopus --enable-libvpx --enable-libx264 --enable-nonfree --enable-version3
  libavutil      52. 55.100 / 52. 55.100
  libavcodec     55. 44.100 / 55. 44.100
  libavformat    55. 21.102 / 55. 21.102
  libavdevice    55.  5.102 / 55.  5.102
  libavfilter     3. 91.100 /  3. 91.100
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 17.104 /  0. 17.104
  libpostproc    52.  3.100 / 52.  3.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x39cb280] decoding for stream 0 failed
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '18579-1386758783533.mp4':
  Metadata:
    major_brand     : f4v 
    minor_version   : 0
    compatible_brands: isommp42m4v 
    creation_time   : 2013-12-11 10:46:22
  Duration: 00:00:29.58, start: 0.000000, bitrate: 134 kb/s
    Stream #0:0(eng): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p(tv), 640x360 [SAR 1:1 DAR 16:9], 121 kb/s, 6.53 fps, 30 tbr, 90k tbn, 60 tbc (default)
    Metadata:
      creation_time   : 2013-12-11 10:46:22
      handler_name    : WowzaMediaServerPro
    Stream #0:1(eng): Audio: speex (spex / 0x78657073), 16000 Hz, mono, s16, 11 kb/s (default)
    Metadata:
      creation_time   : 2013-12-11 10:46:22
      handler_name    : WowzaMediaServerPro

FFprobe - output file:

dead@dead-work-desktop:~/36369/wowzaoutput$ ffprobe v18579-1386758783533.flv
ffprobe version git-2013-11-29-0d640c0 Copyright (c) 2007-2013 the FFmpeg developers
  built on Nov 29 2013 11:54:34 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
  configuration: --extra-libs=-ldl --enable-gpl --enable-libass --enable-libfdk-aac --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libopus --enable-libvpx --enable-libx264 --enable-nonfree --enable-version3
  libavutil      52. 55.100 / 52. 55.100
  libavcodec     55. 44.100 / 55. 44.100
  libavformat    55. 21.102 / 55. 21.102
  libavdevice    55.  5.102 / 55.  5.102
  libavfilter     3. 91.100 /  3. 91.100
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 17.104 /  0. 17.104
  libpostproc    52.  3.100 / 52.  3.100
Input #0, flv, from 'v18579-1386758783533.flv':
  Metadata:
    major_brand     : f4v 
    minor_version   : 0
    compatible_brands: isommp42m4v 
    encoder         : Lavf55.21.100
  Duration: 00:00:51.52, start: 21.840000, bitrate: 366 kb/s
    Stream #0:0: Video: h264 (High), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], 30.33 tbr, 1k tbn, 60 tbc
    Stream #0:1: Audio: aac, 22050 Hz, mono, fltp, 128 kb/s

Full ffmpeg command line output:

dead@dead-work-desktop:~/36369/wowzaoutput$ ffmpeg -y -i 18579-1386758783533.mp4 -c:a libfdk_aac -b:a 128k -ar 22050 -c:v libx264 -pix_fmt yuv420p -s 1920x1080 -framerate 30 1v18579-1386758783533.flv
ffmpeg version git-2013-11-29-0d640c0 Copyright (c) 2000-2013 the FFmpeg developers
  built on Nov 29 2013 11:54:34 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
  configuration: --extra-libs=-ldl --enable-gpl --enable-libass --enable-libfdk-aac --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libopus --enable-libvpx --enable-libx264 --enable-nonfree --enable-version3
  libavutil      52. 55.100 / 52. 55.100
  libavcodec     55. 44.100 / 55. 44.100
  libavformat    55. 21.102 / 55. 21.102
  libavdevice    55.  5.102 / 55.  5.102
  libavfilter     3. 91.100 /  3. 91.100
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 17.104 /  0. 17.104
  libpostproc    52.  3.100 / 52.  3.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x29f3b00] decoding for stream 0 failed
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '18579-1386758783533.mp4':
  Metadata:
    major_brand     : f4v 
    minor_version   : 0
    compatible_brands: isommp42m4v 
    creation_time   : 2013-12-11 10:46:22
  Duration: 00:00:29.58, start: 0.000000, bitrate: 134 kb/s
    Stream #0:0(eng): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p(tv), 640x360 [SAR 1:1 DAR 16:9], 121 kb/s, 6.53 fps, 30 tbr, 90k tbn, 60 tbc (default)
    Metadata:
      creation_time   : 2013-12-11 10:46:22
      handler_name    : WowzaMediaServerPro
    Stream #0:1(eng): Audio: speex (spex / 0x78657073), 16000 Hz, mono, s16, 11 kb/s (default)
    Metadata:
      creation_time   : 2013-12-11 10:46:22
      handler_name    : WowzaMediaServerPro
[libx264 @ 0x29f8f60] using SAR=1/1
[libx264 @ 0x29f8f60] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
[libx264 @ 0x29f8f60] profile High, level 4.0
[libx264 @ 0x29f8f60] 264 - core 140 r2 1ca7bb9 - H.264/MPEG-4 AVC codec - Copyleft 2003-2013 - http://www.videolan.org/x264.html - options: 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=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=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=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, flv, to '1v18579-1386758783533.flv':
  Metadata:
    major_brand     : f4v 
    minor_version   : 0
    compatible_brands: isommp42m4v 
    encoder         : Lavf55.21.102
    Stream #0:0(eng): Video: h264 (libx264) ([7][0][0][0] / 0x0007), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], q=-1--1, 1k tbn, 30 tbc (default)
    Metadata:
      creation_time   : 2013-12-11 10:46:22
      handler_name    : WowzaMediaServerPro
    Stream #0:1(eng): Audio: aac (libfdk_aac) ([10][0][0][0] / 0x000A), 22050 Hz, mono, s16, 128 kb/s (default)
    Metadata:
      creation_time   : 2013-12-11 10:46:22
      handler_name    : WowzaMediaServerPro
Stream mapping:
  Stream #0:0 -> #0:0 (h264 -> libx264)
  Stream #0:1 -> #0:1 (libspeex -> libfdk_aac)
Press [q] to stop, [?] for help
frame=  193 fps= 16 q=-1.0 Lsize=    2300kB time=00:00:29.60 bitrate= 636.4kbits/s    
video:1821kB audio:464kB subtitle:0 global headers:0kB muxing overhead 0.648628%
[libx264 @ 0x29f8f60] frame I:3     Avg QP:15.65  size: 31001
[libx264 @ 0x29f8f60] frame P:110   Avg QP:22.60  size: 12905
[libx264 @ 0x29f8f60] frame B:80    Avg QP:25.85  size:  4399
[libx264 @ 0x29f8f60] consecutive B-frames: 24.9% 56.0% 10.9%  8.3%
[libx264 @ 0x29f8f60] mb I  I16..4: 17.6% 76.5%  5.9%
[libx264 @ 0x29f8f60] mb P  I16..4:  6.9% 17.2%  0.2%  P16..4: 22.4%  3.4%  1.2%  0.0%  0.0%    skip:48.7%
[libx264 @ 0x29f8f60] mb B  I16..4:  0.4%  0.5%  0.0%  B16..8: 22.2%  1.0%  0.1%  direct: 1.4%  skip:74.3%  L0:45.4% L1:52.8% BI: 1.8%
[libx264 @ 0x29f8f60] 8x8 transform intra:71.0% inter:91.3%
[libx264 @ 0x29f8f60] coded y,uvDC,uvAC intra: 16.3% 19.8% 0.9% inter: 4.7% 7.2% 0.0%
[libx264 @ 0x29f8f60] i16 v,h,dc,p: 23% 17%  5% 54%
[libx264 @ 0x29f8f60] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 51% 14% 22%  2%  2%  2%  2%  3%  1%
[libx264 @ 0x29f8f60] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 48% 18% 12%  3%  7%  4%  3%  3%  1%
[libx264 @ 0x29f8f60] i8c dc,h,v,p: 69% 13% 17%  2%
[libx264 @ 0x29f8f60] Weighted P-Frames: Y:0.0% UV:0.0%
[libx264 @ 0x29f8f60] ref P L0: 75.4%  4.7% 14.1%  5.8%
[libx264 @ 0x29f8f60] ref B L0: 88.6% 10.9%  0.5%
[libx264 @ 0x29f8f60] ref B L1: 98.2%  1.8%
[libx264 @ 0x29f8f60] kb/s:504.48

Input file link

share|improve this question
1  
Can you show the full command line output from the actual conversion? –  slhck Dec 11 '13 at 11:19
    
Sure. Added it to my question –  Applejack Dec 11 '13 at 11:24
    
Can you provide input file? Put it on file hosting or something? –  ptQa Dec 11 '13 at 15:53
    
Input file link added to question. –  Applejack Dec 12 '13 at 10:55
    
well, this file is not playable with ffplay or vlc, ffmpeg says: [mov,mp4,m4a,3gp,3g2,mj2 @ 0xe7f200] decoding for stream 0 failed Where did you get this input? –  ptQa Dec 12 '13 at 11:58

1 Answer 1

I have downloaded your .mp4 video sample and it plays very badly unless I change the file-type to .f4v. The video stays frozen for some time while the sound plays, then after about 21 seconds the video starts moving and synchronizes with the sound.

It seems to me that the bad conversion that you get only reflects the real state of your video.

I note that the difference of output duration - output start_time is the same before and after conversion, so it seems that ffmpeg just reflected in its conversion the existing presentation problem found at the start of this video.

I suggest that you find another method of recording from your webcam, because evidently your current method and software generate invalid video files. I also find it strange that the .mp4 file is encoded using the Flash codec of f4v.

share|improve this answer
    
I noted the same about output duration - output start_time. This is not just a video from my webcam, that's just for example. This video was recorded by Wowza Media Server, but I can't even find a tag for Wowza media server here, on Superuser. –  Applejack Dec 17 '13 at 11:11
    
I don't know Wowza, but this example video has a problem at its start. If not all Wowza-generated videos are that way, you will need to post one that plays correctly but still has an output start_time problem after ffmpeg. My guess is that there isn't one. –  harrymc Dec 17 '13 at 12:28
    
Yes, you're right, there isn't one. –  Applejack Dec 17 '13 at 12:34

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