[FFmpeg-trac] #1573(undetermined:new): Enhancing -ss option
FFmpeg
trac at avcodec.org
Wed Jul 25 12:40:58 CEST 2012
#1573: Enhancing -ss option
-------------------------------------+-------------------------------------
Reporter: burek | Type:
Status: new | enhancement
Component: | Priority: wish
undetermined | Version:
Keywords: | unspecified
Blocking: | Blocked By:
Analyzed by developer: 0 | Reproduced by developer: 0
-------------------------------------+-------------------------------------
Consider the following example command line:
{{{
ffmpeg -ss 00:03:00 -i input -vframes 1 out.jpg
}}}
The result will be 1 image frame somewhere around 3rd minute, depending on
gop size of the input, at the last found keyframe, but the seeking will be
extremely fast.
Now consider this line:
{{{
ffmpeg -ss 00:02:30 -i input -ss 00:00:30 -vframes 1 out.jpg
}}}
The output will be the exact image frame at the 3rd minute of the input
and the seeking will be very fast for the first 2 and a half minutes,
following the slow seeking (frame-by-frame) for the next 30 seconds,
resulting in the combination of the fast and accurate seeking.
My question is if the -ss input option (before -i) can be enhanced in such
a way that it automatically adds another -ss output option (after -i)
which will compensate for the difference between the last found keyframe
and the user specified seek time.
For example, if the last found keyframe in that input was at 00:02:57, the
result should be the same as if the user has typed:
{{{
ffmpeg -ss 00:02:57 -i input -ss 00:00:03 -vframes 1 out.jpg
}}}
I hope you get my point. The idea is to seek as fast as possible until the
last keyframe in the specified interval and then to slowly seek to the
precise time point, specified by user, all automatically, without users
having to investigate the input to find out the last keyframe's position.
--
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1573>
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