How to record via IEEE 1394 (Firewire) to Windows XP - Page 204 - AVS Forum | Home Theater Discussions And Reviews
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post #6091 of 6093 Old Yesterday, 01:16 AM
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Huge file size in firewire output from Motorola RNG200

Originally Posted by dr1394 View Post
Comcast is currently converting HD channels from MPEG-2 to H.264 here in the Bay Area. I've been putting it off, but after the latest round of channel conversions, I had to replace my DCH-3200 with an RNG110.

The IEEE1394 port on the RNG110 is enabled, but it's operation is not correct. PAT and PMT is missing and there's a huge amount of stuffing packets on PID 0x1fff. No D-VHS box of any kind can ever work with an RNG110.

However, the video and audio streams are present. With some software trickery, I was able to capture a workable Transport Stream for both MPEG-2 and H.264 channels.

If anyone knows what's going on with my RNG200 DVR from Comcast, it might be you, Ron. I have an old DCX-3401 that I sometimes record stuff to my PC via the firewire port. I also do the same with my newer Comcast box --- an RNG200 (aka DCX-3501). So they are both Motorola critters. Now that most of the channels have been switched to H.264, I have noticed a huge difference in the file sizes when I record H.264 content from the RNG200, versus the DCX-3401.

For example, if I record a 2-hour movie from the Hallmark channel for my stepdaughter, using the DCX-3401, the file is a little over 3GB in size. If I record the same movie, same channel, using the RNG200 (DCX-3501), the file size is over 20GB!!! Usually about 23GB, actually. Both files are quite playable with the VLC Player app.

Ron, you say you have an RNG110 and you noticed "a huge amount of stuffing packets on PID 0x1fff" in the stream you captured to a PC. I am not sophisticated enough to look inside packets (although I do have an IT background), but do you think that what you observed might be what's going on with my gargantuan file sizes from the RNG200?

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post #6092 of 6093 Old Yesterday, 01:45 AM
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It's very likely that it's stuffing packets. An easy test would be to try and compress the large files with PKZIP, 7-Zip or whatever you use.

In general, trying to compress MPEG-2 Transport Streams usually doesn't get you anywhere (since the video and audio is already compressed). But since stuffing packets are almost all 1's, they will compress very well. So the 23 GB files should end up around 3 GB just like you're seeing from the DCX-3401.


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post #6093 of 6093 Old Yesterday, 11:41 PM
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Another easy test to see what's in the file would be to run it through (free) TSReader Lite, which would directly show how many of each type of packet it contains. The non-free, non-Lite version could create a new file with proper PAT and no null ("stuffing") packets. There are other freeware tools for null-packet stripping also.
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