title: FFMPEG: titlecard for concatentaed video results in slow-mo
body: <p>I have three clips I have extracted from a longer video. When I concatenate them together everything works fine, as would be expected since they all came from the same source.</p>
  <p>Now I want to add a title card to the front of the merged video.</p>
  <p>I generated an image in GIMP with the same dimensions as the video frames and then used ffmpeg to generate a 5 sec. video from it. When I concatenated it onto the front of the other three I run into problems.</p>
  <p>The title card segment plays correctly and then the remaining segments are (both video and audio) in slow-mo. Also the titlecard runs longer than 5 sec and the main segment audio starts before the corresponding video.</p>
  <p>I know the problem is with the generation of the title card clip but so far I can't figure out what I am missing. Obviously my bitrates are wrong but how do I get them to match up?</p>
  <p>what I have so far:</p>
  <p>my generation script:</p>
  <pre><code>#!/bin/bash
  
  ffmpeg -y -ss 0:03:33 -t 0:0:33.5 -i seg1.vob -filter:a &quot;volume=4&quot; seg1.mp4
  ffmpeg -y -ss 0:13:25.5 -t 0:0:57 -i seg1.vob -filter:a &quot;volume=4&quot; seg2.mp4
  ffmpeg -y -ss 0:16:25.5 -t 0:0:43 -i seg1.vob -filter:a &quot;volume=4&quot; seg3.mp4
  ffmpeg -y -ss 0:7:10 -t 0:0:10 -i seg1.vob -filter:a &quot;volume=4&quot; -vn -b:a 394k title.mp3
  ffmpeg -y -loop 1 -i title.png -t 0:0:5 -i title.mp3 -c:a aac -b:a 394k -shortest title.mp4 
  ffmpeg -y -f concat -safe 0 -i contents.txt -c copy merged.mp4 
  </code></pre>
  <p>and contents.txt:</p>
  <pre><code>file 'title.mp4'
  file 'seg1.mp4'
  file 'seg2.mp4'
  file 'seg3.mp4'
  </code></pre>
  <p>ffprobe on seg1.mp4:</p>
  <pre><code>Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'seg1.mp4':
    Metadata:
      major_brand     : isom
      minor_version   : 512
      compatible_brands: isomiso2mp41
      encoder         : Lavf58.20.100
    Duration: 00:00:33.52, start: 0.000000, bitrate: 677 kb/s
      Stream #0:0(und): Video: mpeg4 (Simple Profile) (mp4v / 0x7634706D), yuv420p, 720x480 [SAR 32:27 DAR 16:9], 275 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 30k tbc (default)
      Metadata:
        handler_name    : VideoHandler
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, 6 channels, fltp, 394 kb/s (default)
      Metadata:
        handler_name    : SoundHandler
  </code></pre>
  <p>and for title.mp4:</p>
  <pre><code>Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'title.mp4':
    Metadata:
      major_brand     : isom
      minor_version   : 512
      compatible_brands: isomiso2mp41
      encoder         : Lavf58.20.100
    Duration: 00:00:05.02, start: 0.000000, bitrate: 1290 kb/s
      Stream #0:0(und): Video: mpeg4 (Simple Profile) (mp4v / 0x7634706D), yuv420p, 720x480 [SAR 191:194 DAR 573:388], 898 kb/s, 25 fps, 25 tbr, 12800 tbn, 25 tbc (default)
      Metadata:
        handler_name    : VideoHandler
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 389 kb/s (default)
      Metadata:
        handler_name    : SoundHandler
  </code></pre>