[MPlayer-users] Own bitrate calculation (Index size predictable?)
hinrichs at mpia-hd.mpg.de
Tue Aug 19 17:49:00 CEST 2003
For a little script I want to do the bitrate calculation for my own.
This works (nearly) good. The problem I have is the unpredictable size of the
index. For instance I have a movie in MPEG and I want to recode it to fit on
two CDs means a final size of 1400 MByte. After doing the audio pass I get
the size of the audio stream which is in this case 178922029 Bytes and I get
the number of video frames which is 252417. I calculate the video bitrate
with the following formula:
Which results in my case to
Result is 1021392.
When I use this exact bitrate with mencoder the output says the following at
Video stream: 979.712 kbit/s (122464 bps) size: 1289178718 bytes 10527.000
secs 252417 frames
Audio stream: 135.965 kbit/s (16995 bps) size: 178920463 bytes 10527.478
That looks very good, since 1289178718+178920463=1468099181 (1400.09 MByte)
That's very close to what I want to have, but the file size is 1484460110
Bytes which is 1415.69 MByte.
I assume the extra space is for the index so the question is how to predict
the size of the index after the audio pass so that I can calculate a real
Does the size of the index directly depend on the number of video frames or
are there more values to deal with?
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