Changes between Version 18 and Version 19 of Seeking


Ignore:
Timestamp:
Nov 7, 2014, 11:26:24 PM (12 years ago)
Author:
Roger Pack
Comment:

try to call out even more that it is accurate now

Legend:

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  • Seeking

    v18 v19  
    33= Introduction =
    44
    5 If you need to extract only a specific part of your input, you'll need to use the seeking option to get to that specific part in the input first. [http://ffmpeg.org/ffmpeg.html#Main-options The parameter -ss] is used to seek into the input and it can be used in several ways.
     5If you need to extract only a specific part of your input, you'll need to use the seeking option to get to that specific part in the input first. [http://ffmpeg.org/ffmpeg.html#Main-options The parameter -ss] is used to seek within the input and it can be used in several ways.
    66
    7 = Fast seeking =
     7= Input seeking =
    88
    9 The `-ss` parameter needs to be specified before `-i`:
     9The `-ss` parameter needs to be specified somewhere before `-i`:
    1010
    1111{{{
    … …  
    1515[[Image(out.jpg)]]
    1616
    17 This example will produce one image frame (out1.jpg) at the twenty-third minute from the beginning of the movie. The input will be parsed '''using keyframes''', which is '''very fast'''. As of FFmpeg 2.1, when transcoding with `ffmpeg` (i.e. not [https://ffmpeg.org/ffmpeg.html#Stream-copy stream copying]), `-ss` is now accurate even when used as an input option. Previous behavior can be restored with the `-noaccurate_seek` option.
     17This example will produce one image frame (out1.jpg) at the twenty-third minute from the beginning of the movie. The input will be parsed '''using keyframes''', which is '''very fast'''. As of FFmpeg 2.1, when transcoding with `ffmpeg` (i.e. not just [https://ffmpeg.org/ffmpeg.html#Stream-copy stream copying]), `-ss` is now also "frame-accurate" even when used as an input option. Previous behavior (seeking only to the nearest preceding keyframe, even if not precisely accurate) can be restored with the `-noaccurate_seek` option.
    1818
    19 = Slow seeking =
     19= Output seeking =
    2020
    2121The `-ss` parameter needs to be specified after `-i`:
    … …  
    2929This example will also produce one image frame (out2.jpg) precisely at the twenty-third minute from the beginning of the movie.
    3030
    31 Here, the input will be decoded until it reaches the position given by `-ss`. This will be done  '''very slowly''', frame by frame. As of FFmpeg 2.1, the main advantage is that when applying filters to the output stream, the timestamps aren't reset prior to filtering (i.e. when [https://trac.ffmpeg.org/wiki/HowToBurnSubtitlesIntoVideo burning subtitles into a video], you don't need to modify the subtitle timestamps), but the drawback is that it will take a lot of time until it finally reaches that time point. The bigger the seeking time is, the longer you will have to wait.
     31Here, the input will be decoded (and discarded) until it reaches the position given by `-ss`. This will be done  '''very slowly''', frame by frame. As of FFmpeg 2.1, the main advantage is that when applying filters to the output stream, the timestamps aren't reset prior to filtering (i.e. when [https://trac.ffmpeg.org/wiki/HowToBurnSubtitlesIntoVideo burning subtitles into a video], you don't need to modify the subtitle timestamps), but the drawback is that it will take a lot of time until it finally reaches that time point. The bigger the seeking time is, the longer you will have to wait.
    3232
    3333= Combined seeking =