<p>There is a mistake in your ffmpeg command.</p>
<p>The <code>-c</code> option either needs a codec (e.g. <code>-c:v libx264</code>) if you want to encode the video or the special value &quot;copy&quot; if it shouldn't be re-encoded (<code>-c copy</code>).</p>
<p>Using <code>-ss</code> together with <code>-c copy</code> might not be accurate since ffmpeg is forced to only split on i-frames.
But starting on an i-frame should fix the problem with artifacts.</p>

CC BY-SA 4.0
2023-07-29T13:53:45.160Z
Apologies, I was already using "-c copy new_name.mp4". I have updated the question to reflect that.
radumanolescu
CC BY-SA 4.0
2023-07-21T11:23:25.727Z
2023-07-21T11:23:25.727Z
drake7
<p>I cut videos using the command below, and I sometimes find that the resulting video has imperfections at the beginning (square artifacts in the image). If I advance the start time parameter value (<code>START_AT_SECONDS</code>) by a few seconds (usually 1..3s), the artifacts go away.</p>
<p>Is there a way to avoid the hit-and-miss, e.g. to know in advance that <code>START_AT_SECONDS=53</code> works but <code>START_AT_SECONDS=52</code> will give artifacts? Is there an option that means &quot;START_AT_SECONDS=52, or later as needed to make a good cut&quot;?</p>
<pre><code>ffmpeg -ss START_AT_SECONDS -i &quot;some_file_name.mp4&quot; -t DURATION_SECONDS -c copy &quot;new_name.mp4&quot;
</code></pre>

<ffmpeg>
ffmpeg - Finding the right point to cut
radumanolescu
# ffmpeg - Finding the right point to cut

(Asked by: username_0 on 2023-07-14)

I cut videos using the command below, and I sometimes find that the resulting video has imperfections at the beginning (square artifacts in the image). If I advance the start time parameter value (START_AT_SECONDS) by a few seconds (usually 1..3s), the artifacts go away.
Is there a way to avoid the hit-and-miss, e.g. to know in advance that START_AT_SECONDS=53 works but START_AT_SECONDS=52 will give artifacts? Is there an option that means "START_AT_SECONDS=52, or later as needed to make a good cut"?
ffmpeg -ss START_AT_SECONDS -i "some_file_name.mp4" -t DURATION_SECONDS -c copy "new_name.mp4"

**Tags:** ffmpeg


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## 1 answers

### Answer by username_1 on 2023-07-21. Score: 0

There is a mistake in your ffmpeg command.

The `-c` option either needs a codec (e.g. `-c:v libx264`) if you want to encode the video or the special value "copy" if it shouldn't be re-encoded (`-c copy`).

Using `-ss` together with `-c copy` might not be accurate since ffmpeg is forced to only split on i-frames.
But starting on an i-frame should fix the problem with artifacts.

> **Comments:**
> **username_0**: Apologies, I was already using "-c copy new_name.mp4". I have updated the question to reflect that.  

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