<p>I saw this answer <a href="https://video.stackexchange.com/questions/29904/ffmpeg-batch-overlay-error-cannot-find-a-matching-stream-for-unlabeled-input-p">ffmpeg batch overlay Error: &quot;Cannot find a matching stream for unlabeled input pad 1 on filter Parsed_overlay_0&quot;</a> for same error message but doesn't seem to be same case :</p>
<p>I first converted 2 gifs of same width and height to mp4 using ffmpeg options</p>
<pre><code>ffmpeg -i video1.gif -movflags faststart -pix_fmt yuv420p -vf &quot;scale=trunc(iw/2)*2:trunc(ih/2)*2&quot; video1.mp4
ffmpeg -i video2.gif -movflags faststart -pix_fmt yuv420p -vf &quot;scale=trunc(iw/2)*2:trunc(ih/2)*2&quot; video2.mp4
</code></pre>
<p>afterwards I joined with</p>
<pre><code>ffmpeg -i video1.mp4 -i video2.mp4 -filter_complex &quot;concat=n=2:v=1:a=1&quot; -f MP4 -y video.mp4
</code></pre>
<p>But I got error</p>
<pre><code>Cannot find a matching stream for unlabeled input pad 1 on filter Parsed_concat_0
</code></pre>
<p>with other mp4 in the past joining works so I don't understand why.</p>

CC BY-SA 4.0
2020-11-20T15:08:14.353Z
Share full command that you tried.
Gyan
CC BY-SA 4.0
2020-11-20T17:23:04.047Z
@Gyan updated my question
user310291
<ffmpeg>
Cannot find a matching stream for unlabeled input pad 1 on filter Parsed_concat_0 (a different case)
user310291
# Cannot find a matching stream for unlabeled input pad 1 on filter Parsed_concat_0 (a different case)

(Asked by: username_0 on 2020-11-20)

I saw this answer ffmpeg batch overlay Error: "Cannot find a matching stream for unlabeled input pad 1 on filter Parsed_overlay_0" for same error message but doesn't seem to be same case :
I first converted 2 gifs of same width and height to mp4 using ffmpeg options
ffmpeg -i video1.gif -movflags faststart -pix_fmt yuv420p -vf "scale=trunc(iw/2)*2:trunc(ih/2)*2" video1.mp4
ffmpeg -i video2.gif -movflags faststart -pix_fmt yuv420p -vf "scale=trunc(iw/2)*2:trunc(ih/2)*2" video2.mp4

afterwards I joined with
ffmpeg -i video1.mp4 -i video2.mp4 -filter_complex "concat=n=2:v=1:a=1" -f MP4 -y video.mp4

But I got error
Cannot find a matching stream for unlabeled input pad 1 on filter Parsed_concat_0

with other mp4 in the past joining works so I don't understand why.

**Tags:** ffmpeg

> **Comments:**
> **username_1**: Share full command that you tried.  
> **username_0**: @username_1 updated my question  

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## 0 answers

