Why does FFmpeg append blank black video to the end of my MP4 files when compressed from MOV?

I have several large MOV files that I want to compress to MP4.

Unfortunately, when I use FFmpeg, it appends lots of black (blank) video at the end.

(The destination file is longer than the source file.)

For example, I have a file that is 02:22:01 in duration (and the FFmpeg output logs confirm this).

But when I run the following command (which takes more than 20 minutes even on "ultrafast"), I get an MP4 file that looks mostly good but has lots of black frames appended to the end such that the total video duration becomes 3:59:59.

ffmpeg -i "F:\video_project\uncompressed\Tape_12.mov" -vcodec libx264 -preset ultrafast -crf 18 -n -threads 16 -f mp4 "F:\video_project\compressed\Tape_12.mp4" 2>&1

This happens with my other MOV-to-MP4 conversions too. The duration of black video appended to the end can be 20 to 80+ minutes long (it's not the same for each different video).

What am I doing wrong?

My logs are here.

P.S. I'm using PowerShell 4 in Windows 7.

Update:

In response to LordNeckBeard, when I run ffmpeg.exe -i F:\video_project\compressed\Tape_12.mp4, the result is:

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'F:\video_project\compressed\Tape_12.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf55.22.101
  Duration: 03:59:59.94, start: 0.033333, bitrate: 5389 kb/s
    Stream #0:0(eng): Video: h264 (High 4:2:2) (avc1 / 0x31637661), yuv422p, 720x480 [SAR 10:11 DAR 15:11], 5252 kb/s, 29.97 fps, 29.97 tbr, 11988 tbn, 59.94 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(eng): Audio: aac (mp4a / 0x6134706D), 48000 Hz, mono, fltp, 128 kb/s (default)
    Metadata:
      handler_name    : SoundHandler

In response to Rajib, when I run ffmpeg.exe -i F:\video_project\uncompressed\Tape_12.mov, the result is:

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'F:\video_project\uncompressed\Tape_12.mov':
  Metadata:
    creation_time   : 2014-01-05 02:35:17
  Duration: 02:22:01.04, start: -6.064083, bitrate: 51226 kb/s
    Stream #0:0(eng): Video: dvvideo (dvc  / 0x20637664), yuv411p, 720x480 [SAR 8:9 DAR 4:3], 28771 kb/s, SAR 10:11 DAR
15:11, 29.97 fps, 29.97 tbr, 2997 tbn, 29.97 tbc (default)
    Metadata:
      creation_time   : 2014-01-05 06:35:18
      handler_name    : Apple Alias Data Handler
    Stream #0:1(eng): Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, mono, s16, 768 kb/s (default)
    Metadata:
      creation_time   : 2014-01-05 06:35:18
      handler_name    : Apple Alias Data Handler
    Stream #0:2(eng): Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, mono, s16, 768 kb/s (default)
    Metadata:
      creation_time   : 2014-01-05 06:35:18
      handler_name    : Apple Alias Data Handler

Ryan

Posted 2014-03-06T22:08:43.053

Reputation: 959

What does ffmpeg say of the duration of the output? ffmpeg -i Tape_12.mp4 What is telling you the duration is 3:59:59? All information should be included within your question instead of relying on external resources (you can omit the multiple repeating frame= lines). – llogan – 2014-03-06T23:41:21.690

@LordNeckbeard, ffmpeg and Windows Explorer ("Details" view) both say that the mp4 duration is 3:59:59. I'll paste the result of your suggested query above. – Ryan – 2014-03-07T00:22:57.110

@Rajib I added the information that you requested. – Ryan – 2014-03-07T03:46:43.267

@Rajib I did as you instructed, and the resulting videos were identical to the MP4s from before; each had the same amount of black video appended as each had before. The logs are here: https://drive.google.com/folderview?id=0B9iQ20nrMNYAakZSenZNRTBjRE0&usp=sharing

– Ryan – 2014-03-07T04:53:02.633

Well the workaround is to put -t 02:22:01.04 in the command explicitly, but it does not solve the issue. – Rajib – 2014-03-07T05:16:49.167

I think my problem is related to the fact that the MOV file seems to have a "start" value of -6.064083 (as shown in my question). I don't know why. Since it has an incorrect start time, I bet it also has an artificial "end" time. Then FFmpeg creates an mp4 file for the full duration instead of the actual playable duration. See also: http://stackoverflow.com/questions/10640088/why-does-ffmpeg-report-different-durations

– Ryan – 2014-03-11T16:22:05.897

Why does FFmpeg append blank black video to the end of my MP4 files when compressed from MOV?

Answers