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89 lines
2.9 KiB
89 lines
2.9 KiB
4 years ago
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5 step guide for cluster batch encoding with transcode 0.6.x:
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-------------------------------------------------------------
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Note: this feature is only available for transcode-0.6.0pre2 and higher!
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pre-processing:
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===============
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(1) we first rip the desired DVD title into a work directory, containing
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only the VOB chunks for transcode's directory mode. This
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directory should be accessable for all nodes via NFS.
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example:
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========
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tccat -i /dev/dvd -T 1,-1 | split -b 1024m - dvd_title/part-
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(2) next we need to create a navigation file to access all the
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VOB chunks with frame accurate navigation.
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example:
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========
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tccat -i dvd_title/ | tcdemux -W >nav_file
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distributed encoding:
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=====================
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(3) we need to decide, how many chunks we want to create for
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distributed encoding. This number should not be too high, in case
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you prefer 2-pass encoding. Otherwise, it may depend on the nodes
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in our cluster. Assume we want 8 chunks with approx.
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25k frames.
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For each chunk, switch to a node and invoke transcode with your
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favorite options. In addition, use the new -W option:
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example:
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========
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transcode -i dvd_title/ -W X,8,nav_file -o part-X.avi (.....)
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and repeat this for X=0,1,2,...,7.
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Note, this will transcode the video only. Audio is done for the
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entire stream in the last step with X=8. Repeat this step in case of
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2-pass encoding. However, in this case we need to specify different
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filenames for multi-pass encoding logfile with option -R.
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post-processing:
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================
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(4) merge the resulting files
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example:
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========
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avimerge -o tmp_movie.avi -i dvd_title/part-*
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(5) finally, the audio has to be encoded separately and multiplexed in one
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step
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example:
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========
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transcode -p dvd_title/ -W 8,8,nav_file -i tmp_movie.avi -P 1
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-x avi,vob -y raw -o movie.avi -u 50
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This command will pass-through the video, extract the audio track
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and multiplex both into movie.avi. Increasing the number of buffer
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for audio processing only will boost the performance.
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To tell transcode to process all chunks, the first parameter to -W is
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identical to the number of chunks.
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----------------------------------------------------------------------------
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Q: Why not use -c 0-25000, ... with 0.5.x?
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A: Well, the problem is seeking to large frame numbers requires decoding
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all previous frames, which takes way too long.
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Q: Why not transcoding the audio with step (3)?
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A: This may lead to AV out of sync on chunk boundaries, since a
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MP3 frame requires a certain amount of PCM data and the encoder runs
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on different nodes. If you need it, use PCM, this will work fine.
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Q: Will it work for NTSC?
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A: Not tested very well. It may or may not work.
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----------------------------------------------------------------------------
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