On Mon, Sep 8, 2014, at 12:04 PM, Harold Goranson wrote: >I wish to recode them as modern mp4 >to 300p high and as wide as required >to maintain correct aspect ratio, rounded >to the nearest 2p. No sound, but all other >qualities the same.
Lou replied: You can use the scale filter: -vf scale=300:-2 https://ffmpeg.org/ffmpeg-filters.html#scale +++++ ffmpeg -i Source.mkv scale=300:-3 Result.mpg This works perfectly. Thank you. Now I need to elaborate the process. The use case has two goals: — a consistent source for an elaborate process that extracts slices from frames selected from every second and recomposes them. These scripts are a separate process to create a scrubber strip. For this it is desirable that frames be of high quality. I suppose that reducing the framerate to 24fps is useful. It seems that VBR is desirable here. Encoding time is not a constraint. — the source for streaming a 300p tall version of the film, using h264. A ramble around references gives no clear guidance on this, but it appears that regular periodic I-frames (say every 4 seconds) and heavy use of B-frames is desirable. VBR seems acceptable here as well, using two-pass encoding controlled by the average bitrate setting. Are these two use cases in conflict? It is easy enough to make two products. Am I right in thinking that reduced frame rate and 2-pass VBR is desirable? What would the command look like to accomplish this? Thanks.
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