<p>when I muxyng .mkv file and .ac3 file without converting I had next errors:</p>

<ul>
<li>[ac3]Estimating duration from bitrate, this may be inaccurate</li>
<li>[matroska]Starting new cluster due to timestampe </li>
<li>muxing overhead: 0.078666%</li>
</ul>

<p>ac3 error output appears before .ac3 file information
<a href="https://i.sstatic.net/7X2p2.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/7X2p2.jpg" alt="enter image description here"></a></p>

<p>mkv and muxing overhead in end of console output appears
<a href="https://i.sstatic.net/PfGuK.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/PfGuK.jpg" alt="enter image description here"></a></p>

<p>Script that i use:</p>

<pre><code>ffmpeg -i input1.mkv -i input2.ac3 -map 0:v -map 1:a -map 0:a -map 0:s -c:v copy
-c:a:1 copy -c:s copy -metadata:s:a:0 language={lang} -metadata:s:a:0 title="title1"
-metadata:s:a:1 title="title2" output.mkv
</code></pre>

<p>I try to copy .mkv file and .ac3 separately and .mkv copying only with muxing overhead and .ac3 cppying with ac3 error(without muxing overhead).
Could you explain what the reason of this problem, and help me with it? 
Also <strong>after muxing in the end of output video file absent small part of audio stream from second file! How To manage with this issue?</strong></p>

<p>Thanks</p>

CC BY-SA 3.0
2017-08-19T13:53:41.267Z
There aren't any errors, only info messages.
Gyan
CC BY-SA 3.0
2017-08-19T14:22:14.890Z
Yes, but there is no small part of audio stream in the end of output film
ZakZand
CC BY-SA 3.0
2017-08-19T20:57:24.270Z
Run `ffmpeg -i input2.ac3 -c copy input2.mp4` and then try your command with this new file.
Gyan
CC BY-SA 3.0
2017-08-20T21:55:02.300Z
Mulvya, no, I do it even with ac3 encoding, but in the end, when I copy this streams in 1 output files I have 3 minutes empty audio stream in the end of film. As I understand this issue appears because size of concrete video frame not comparable with audio stream frame... Do you have any idea what argument should I set in script to solve this issue? May be set bitrate or buffer size?
ZakZand
CC BY-SA 3.0
2017-08-21T05:01:13.357Z
Share the full log of the command.
Gyan
CC BY-SA 3.0
2017-09-10T18:04:24.413Z
What part of console log you interest in?
ZakZand
<ffmpeg>
[ac3]Estimating duration from bitrate, [matroska]Starting new cluster due to timestampe and muxing overhead errors when muxing .mkv and .ac3 in .mkv
ZakZand
# [ac3]Estimating duration from bitrate, [matroska]Starting new cluster due to timestampe and muxing overhead errors when muxing .mkv and .ac3 in .mkv

(Asked by: username_0 on 2017-08-19)

when I muxyng .mkv file and .ac3 file without converting I had next errors:

[ac3]Estimating duration from bitrate, this may be inaccurate
[matroska]Starting new cluster due to timestampe 
muxing overhead: 0.078666%

ac3 error output appears before .ac3 file information

mkv and muxing overhead in end of console output appears

Script that i use:
ffmpeg -i input1.mkv -i input2.ac3 -map 0:v -map 1:a -map 0:a -map 0:s -c:v copy
-c:a:1 copy -c:s copy -metadata:s:a:0 language={lang} -metadata:s:a:0 title="title1"
-metadata:s:a:1 title="title2" output.mkv

I try to copy .mkv file and .ac3 separately and .mkv copying only with muxing overhead and .ac3 cppying with ac3 error(without muxing overhead).
Could you explain what the reason of this problem, and help me with it? 
Also after muxing in the end of output video file absent small part of audio stream from second file! How To manage with this issue?
Thanks

**Tags:** ffmpeg

> **Comments:**
> **username_1**: There aren't any errors, only info messages.  
> **username_0**: Yes, but there is no small part of audio stream in the end of output film  
> **username_1**: Run `ffmpeg -i input2.ac3 -c copy input2.mp4` and then try your command with this new file.  
> **username_0**: Mulvya, no, I do it even with ac3 encoding, but in the end, when I copy this streams in 1 output files I have 3 minutes empty audio stream in the end of film. As I understand this issue appears because size of concrete video frame not comparable with audio stream frame... Do you have any idea what argument should I set in script to solve this issue? May be set bitrate or buffer size?  
> **username_1**: Share the full log of the command.  
> **username_0**: What part of console log you interest in?  

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## 0 answers

