<p>By default, ffmpeg treats image sequence and raw video inputs as having a native rate of 25 fps unless told otherwise. So, the <code>-r 50</code> duplicates each frame.</p>

<p>Use</p>

<pre><code>ffmpeg -framerate 50 -i imageSeq-%06d.png -vcodec png -pix_fmt rgb32 -y video.mov
</code></pre>

<p>You can skip the <code>-r 50</code> since ffmpeg will use the input's framerate.</p>

CC BY-SA 3.0
2017-11-23T16:08:24.670Z
2017-11-23T16:08:24.670Z
Gyan
<p>I'm using ffmpeg to convert a <code>PNG</code> image sequence into a <code>.mov</code> file with alpha channel for use in my NLE.</p>
<p>The <code>PNG</code> sequence was rendered out of DashWare where it was generated in sync with a 4m35s (approx) 1080p50 video clip.</p>
<p>As expected the image sequence consisted of just over 13,750 images.</p>
<p>I used the following command to convert these into the required <code>PNG</code> encoded, uncompressed <code>RGBA</code> (rgb32) <code>.mov</code> file.</p>
<pre><code>ffmpeg -i imageSeq-%06d.png -vcodec png -r 50 -pix_fmt rgb32 -y video.mov
</code></pre>
<p>And the file converted OK <em>but</em> it's duration came out at 9m10s - exactly double what it should have been.</p>
<p>By my reckoning 4m35s at 50fps is: <code>((4x60)+35)x50</code> which is 13750 frames/images. So why did the duration double in conversion with the above command?</p>

<ffmpeg><quicktime>
ffmpeg **doubled** my duration
Fat Monk
# ffmpeg **doubled** my duration

(Asked by: username_0 on 2017-11-23)

I'm using ffmpeg to convert a PNG image sequence into a .mov file with alpha channel for use in my NLE.
The PNG sequence was rendered out of DashWare where it was generated in sync with a 4m35s (approx) 1080p50 video clip.
As expected the image sequence consisted of just over 13,750 images.
I used the following command to convert these into the required PNG encoded, uncompressed RGBA (rgb32) .mov file.
ffmpeg -i imageSeq-%06d.png -vcodec png -r 50 -pix_fmt rgb32 -y video.mov

And the file converted OK but it's duration came out at 9m10s - exactly double what it should have been.
By my reckoning 4m35s at 50fps is: ((4x60)+35)x50 which is 13750 frames/images. So why did the duration double in conversion with the above command?

**Tags:** ffmpeg, quicktime


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## 1 answers

### Answer by username_1 on 2017-11-23. Score: 5 | Accepted answer

By default, ffmpeg treats image sequence and raw video inputs as having a native rate of 25 fps unless told otherwise. So, the -r 50 duplicates each frame.
Use
ffmpeg -framerate 50 -i imageSeq-%06d.png -vcodec png -pix_fmt rgb32 -y video.mov

You can skip the -r 50 since ffmpeg will use the input's framerate.


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