[FFmpeg-user] Removing parts of a video using the select filter

Michael Koch astroelectronic at t-online.de
Sun Jan 9 13:33:51 EET 2022

Am 09.01.2022 um 11:43 schrieb MacFH - C E Macfarlane - News:
> On 08/01/2022 23:43, amindfv--- via ffmpeg-user wrote:
>> On Sat, Jan 08, 2022 at 08:20:46PM +0000, MacFH - C E Macfarlane - 
>> News wrote:
>>> To select parts of a video, I use ...
>>> FFMPEG -ss <start-time> -i <input> -codec copy -to <end> <output>
>>> ... however it's tedious, because with this method the video will 
>>> only break
>>> at certain points between compression units (can't remember the proper
>>> terminology), and it can take some experimentation to find the precise
>>> timing of these to get the audio right as well, and often, because 
>>> of the
>>> way the compression works, the first extracted frame is often an 
>>> unwanted
>>> last frame of a previous scene.
>>> I have long lamented that FFMPEG doesn't make this both easier and 
>>> to allow
>>> greater resolution, if necessary recreating the start and end 
>>> compression
>>> units to get the exact timing wanted.
>> If you get rid of the "-codec copy" you can have any precision you'd 
>> like.
> But the entire video will be re-encoded, which is undesirable because, 
> as the codecs use lossy compression, there will be further degradation 
> of the entire video clip just gain some precision at each end.

Is it possible to re-encode only the beginning and the end, and use 
-codec copy for the central part?


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