<p>Every time I concat, I quickly run it thru this awesome little freeware from Mean beforehand, <a href="http://avidemux.sourceforge.net/" rel="nofollow noreferrer">avidemux</a>, (MP4 Muxer-&gt;Move index to the beginning of the file-&gt;Save) and it fixes the <em>majority</em> of any concat issues I've run into. Not sure if it will fix <em>your</em> issue, but it can't hurt and somewhere down the line avidemux <em>will</em> come in handy and fix a concat issue if you're having one. Shoutout to Mean for such a helpful piece of freeware!</p>

CC BY-SA 4.0
2021-02-06T04:34:41.570Z
wonder if this is the same in ffmpeg: ffmpeg -i input.mp4 -codec copy -movflags +faststart output.mp4 (stackoverflow.com/questions/7614635/…) I tried this in ffmpeg and no difference in results. I'll try avidemux and see if its any different.
Sun
CC BY-SA 4.0
2021-02-04T12:20:53.527Z
2021-02-04T12:20:53.527Z
John Alderson
<p>I have a Zoom video that I &quot;cut&quot; into two videos:</p>
<pre><code>ffmpeg -i 0131.mp4 -ss 55 -t 38:52 -codec copy 0131-1.mp4
ffmpeg -i 0131.mp4 -ss 40:00 -t 1:52 -codec copy 0131-2.mp4
</code></pre>
<p>I then merged into one using [concat demuxer][1] in ffmpeg.</p>
<p>The merged video plays, but the first 15 seconds of the merged video is blank (audio plays okay). What do I need to do so that first 15 seconds of the merged video also displays? Is this due to a &quot;keyframe&quot; not appearing for 15 seconds after my cut point?</p>
<blockquote>
<pre><code>Stream #0:0(und): Audio: aac (LC) (mp4a / 0x6134706D), 32000 Hz, mono, fltp, 126 kb/s (default)
Metadata:
  creation_time   : 2021-01-31T21:53:20.000000Z
  handler_name    : AAC audio
Stream #0:1(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720, 741 kb/s, 25 fps, 25 tbr, 30k tbn, 60k tbc (default)
Metadata:
  creation_time   : 2021-01-31T21:53:20.000000Z
  handler_name    : H.264/AVC video
  encoder         : AVC Coding
Stream #0:2(und): Data: bin_data (text / 0x74786574), 0 kb/s
Metadata:
  creation_time   : 2021-01-31T21:53:20.000000Z
  handler_name    : Text
</code></pre>
</blockquote>

<ffmpeg><editing>
How do I make a trimmed video show the missing frames from a Zoom recording using ffmpeg?
Sun
# How do I make a trimmed video show the missing frames from a Zoom recording using ffmpeg?

(Asked by: username_0 on 2021-02-01)

I have a Zoom video that I "cut" into two videos:
ffmpeg -i 0131.mp4 -ss 55 -t 38:52 -codec copy 0131-1.mp4
ffmpeg -i 0131.mp4 -ss 40:00 -t 1:52 -codec copy 0131-2.mp4

I then merged into one using [concat demuxer][1] in ffmpeg.
The merged video plays, but the first 15 seconds of the merged video is blank (audio plays okay). What do I need to do so that first 15 seconds of the merged video also displays? Is this due to a "keyframe" not appearing for 15 seconds after my cut point?

Stream #0:0(und): Audio: aac (LC) (mp4a / 0x6134706D), 32000 Hz, mono, fltp, 126 kb/s (default)
Metadata:
  creation_time   : 2021-01-31T21:53:20.000000Z
  handler_name    : AAC audio
Stream #0:1(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720, 741 kb/s, 25 fps, 25 tbr, 30k tbn, 60k tbc (default)
Metadata:
  creation_time   : 2021-01-31T21:53:20.000000Z
  handler_name    : H.264/AVC video
  encoder         : AVC Coding
Stream #0:2(und): Data: bin_data (text / 0x74786574), 0 kb/s
Metadata:
  creation_time   : 2021-01-31T21:53:20.000000Z
  handler_name    : Text

**Tags:** ffmpeg, editing


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## 1 answers

### Answer by username_1 on 2021-02-04. Score: 0

Every time I concat, I quickly run it thru this awesome little freeware from Mean beforehand, [avidemux](http://avidemux.sourceforge.net/), (MP4 Muxer->Move index to the beginning of the file->Save) and it fixes the *majority* of any concat issues I've run into. Not sure if it will fix *your* issue, but it can't hurt and somewhere down the line avidemux *will* come in handy and fix a concat issue if you're having one. Shoutout to Mean for such a helpful piece of freeware!

> **Comments:**
> **username_0**: wonder if this is the same in ffmpeg: ffmpeg -i input.mp4 -codec copy -movflags +faststart output.mp4 (stackoverflow.com/questions/7614635/…) I tried this in ffmpeg and no difference in results. I'll try avidemux and see if its any different.  

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