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| alazarus |
| Posted: Oct 17 2002, 04:12 AM |
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Unregistered
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I had a Divx avi that was 699 MB.
I then split it into three pieces 2 large one small in the center which had a bad frame. I did this using direct stream copy. I then used Koala player to repair the damadged section and then joined the three back together again.
I was suprised to find that the resulting avi was now 703MB.
This kind of put me off because I was no longer able to write it to one CD without overburning, which is not a practice I condone.
What is the extra space that virtualdub is creating and how can I get rid of it?
Thanks. |
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| ChristianHJW |
| Posted: Oct 17 2002, 04:19 PM |
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Advanced Member
Group: Moderators
Posts: 1768
Member No.: 2
Joined: 7-July 02
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Its probably the repairing that resultet in extra size of the middle portion, like only keyframes ? what were the sizes of the 3 portions before you joined them ?
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| alazarus |
| Posted: Oct 24 2002, 03:16 AM |
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Unregistered
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Have not had a chance to get back to the problem until today.
I am trying to repair another file 669MB.
I split it into seven parts 1,2e,3,4e,5,6e,7.
The e denotes a section with an error in it.
I made copies of 2e,4e, & 6e.
I used direct stream processing for both video and Audio.
The total combined size of these 7 files was 702 MB.
I then repaired 2e,4e,6e and there sizes did not increase they remained
at 2.4 MB 1.4MB and 1.29MB respectively. 2e = 20 sec , 4e&6e = 10 second each.
When I rejoined the seven pieces the new files size was 702 MB.
I then built a test avi from the spare copies of the 2e,4e, & 6e.
The size of this test file was also 702 MB.
Therefore, just by spliting a file up and recombining it in direct stream copy
mode the size is increased. I was wondering where this space is and how
I could reclaim it.
The AVI at 702 MB is to large to fit on a CD-R.
Thanks,
Asher
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| alazarus |
| Posted: Oct 24 2002, 11:30 PM |
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Quick Correction the avi in the previous message is infact 699 MB not 669 MB.
I looked under file information under the new file vs the old file.
For the Video stream the the only changes
are slightly less space used in for both delta and key frames
this is less than 20k size difference.
For the Audio stream the space used by the audio is exacley the same.
However there is an astronomical difference in the # of audio frames.
The origional file had only 12881 audio frames the new file has 154401
audio frames.
new size = 736,739,328 old size = 733,282,304 diff = 3457024
new frames = 154401 old frames = 12881 diff = 141520
So for this difference to be accounted for by the increase in index size only
would require a difference of 24 bytes per audio frame.
Another question why does virtual dub get pissed off with variable rate
mp3 audio tracks and treat then like fixed bit rate MP3s. This results
in the audio getting out of sync with the video.
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| alazarus |
| Posted: Oct 24 2002, 11:40 PM |
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So This in fact was the case I changed the Audio interleave to
every 10 video frames and the resulting file was only 699 MB.
I'm still curious about the Variable bitrate MP3s. |
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| fccHandler |
| Posted: Oct 25 2002, 03:33 AM |
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Administrator n00b
Group: Moderators
Posts: 3961
Member No.: 280
Joined: 13-September 02
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MPEG audio is divided into frames just like video. And just like video, every frame has a common duration (analogous to a video's "frame rate"). This is true of CBR and VBR MPEG audio.
But with CBR MPEG audio, each frame also has a common size (in bytes). This makes it easy to seek to any desired position in time, using simple math. The problem with VBR audio is that frames may be different sizes. Many programs (VirtualDub included) fail to seek properly when the size of every audio frame varies.
The only sure fix I know is to decompress the audio and recompress it to CBR. Unfortunately, some quality is lost in the process.
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May the FOURCC be with you... |
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| toogle |
| Posted: Jan 5 2003, 10:53 AM |
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Unregistered
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This may sound too simple. Why not just use 800 MB cdr? |
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