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  1. Member
    Join Date
    Feb 2008
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    United States
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    I had to get a new DVR from my cable company because they switched to H.264 from MPEG-2. The good news is the new DVR still has a firewire port like my old DVR so I can capture the transport stream using CapDVHS.

    When I use CapDVHS, a stream of 27 Mbps is dumped, but the actual bitrate is around 3 Mbps. The other 24 Mbps are null packets. I can remove the null packets with software, like VideoReDo, after the capture to get the 3 Mbps stream, but the problem is 27 Mbps is huge on hard drive space for hours of capturing and I would like to avoid the extra software step.

    Is there any setting in CapDVHS that will omit or strip the null packets during capture?
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  2. Formerly 'vaporeon800' Brad's Avatar
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    Apr 2001
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    Vancouver, Canada
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    Doubt it, given what a barebones ancient software CapDVHS is. I think you should just be grateful that it still works and that VideoReDo can do the post-processing you want!

    But hopefully someone comes along with a definitive answer.
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  3. Dinosaur Supervisor KarMa's Avatar
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    Jul 2015
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    US
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    Might try capturing to a folder or drive with NTFS compression enabled. The compression function that comes with NTFS is designed to be extremely fast on the encode and decode, which also gives it poor compression ratios. But if the videos really are mostly NULL filler data then you should see some serious data compression.

    I use it more for computer programs and games which tend to be compressible, and considering the bottleneck these days is the HDD it makes sense for me to trade slightly more CPU load decoding for faster read times in effect. I tend to believe that NTFS compression will make fragmentation worse on the partition it's enabled on, which is not great considering NTFS fragmentation is bad to begin with. It's also not recommended for SDDs, as it writes twice to the drive.

    https://support.microsoft.com/en-us/help/251186/best-practices-for-ntfs-compression-in-windows

    Click image for larger version

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    Notice how the actual size (decompressed size) is larger than the size on the disk, because the size on the disk is the compressed size. With your NULL videos, you should see quite a bit more compression happen. I also defragmented the drive after doing this. You can also just try this out by compression a single individual file with these NULL packets, to see what kind of compression is possible.

    Apart from that I doubt you can do anything to automatically remove the NULL data. I know DVB Viewer will remove NULL data but I don't think it will work for your firewire set up.
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