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Old 04-21-2015, 12:11 PM   #1
Scott9mm
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Compress TiVo Files?

I suspect this has been covered well in the past but I'm a Johnny-come-lately and I haven't found the answers yet.

I have recorded analog TiVo for years at basic quality and was satisfied with the picture quality and file size, some of which I archive for later viewing.
Now, my cable company is going all-digital so the resulting files are about 10x the size of my old analog files. I upgraded my Series 3 HD TiVo to a (used) Series 4 with a 4TB drive so now my "new" TiVo can hold enough programs before overwriting them.

But the huge digital HD files are going to be too much for my NAS so I'd like to compress them. I experimented with TiVo Desktop Plus and find the iPad setting produces files comparable (in size and quality) to my old analog files. I experimented with VideoReDo but haven't broken the code on that yet (guess it's time to read the book).

So here's what I'd like to know:
(1) Firstly which file types are compatible with the S4 TiVo such that I can reload and play them on the TiVo? Or put another way, what file types should I avoid?
(2) Second, What are the recommended transcode settings to get the best quality/file-size tradeoff? I haven't tried pyTiVo yet but I have tried kmttg, VRD, and Desktop Plus and they all have a set of predefined transcode options.
(3) Finally, is there a significant transcode speed difference between the various tools?

Thanks in advance for whatever insight/experience you may offer.

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Old 04-21-2015, 04:00 PM   #2
ThAbtO
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.TiVo files is just .MPG with a Tivo encryption layer.

Decrypting with TivoDecode or KMTTG (which use TivoDecode) will allow transfer to Tivo even though the MAK (Media Access Key) have changed.

You can use VideoReDo to edit out commercials which will take a significant bite off the file size.

PyTivo does better than Tivo Desktop. Files such as .MP4, MKV (Blu-Ray files) will work under Pytivo, Not sure if TDP will work with .MKV.

Some cable channels may be/have moved to MPEG4.

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Old 04-21-2015, 05:22 PM   #3
Scott9mm
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Quote:
Originally Posted by ThAbtO View Post
.TiVo files is just .MPG with a Tivo encryption layer.

Decrypting with TivoDecode or KMTTG (which use TivoDecode) will allow transfer to Tivo even though the MAK (Media Access Key) have changed.

You can use VideoReDo to edit out commercials which will take a significant bite off the file size.

PyTivo does better than Tivo Desktop. Files such as .MP4, MKV (Blu-Ray files) will work under Pytivo, Not sure if TDP will work with .MKV.

Some cable channels may be/have moved to MPEG4.
Thanks. I knew some of this (like mpeg2, decode, and VRD). While the iPad format in TiVo Desktop produces files comparable to basic analog in quality and size, it seems the TiVo transcodes that format when it transfers from a PC to the TiVo (at least using Desktop: the transfer is slow and the file grows by a factor of 5). The Streambaby Wiki page on code.google provides some compatibility clues but video coding and file format must be a complex subject.

I'll probably find a good format eventually by trial and error. I was just hoping to tap into the brain trust here and shortcut my brute-force trial and error.

Someone posted on this site that all TiVo Desktop Plus conversions for portable devices produce the same size file, but I find that not to be the case. There is at least a factor of three variation in file size and image quality. Then there is the issue of which formats will reload to Tivo without transcoding again.

Back to trial and error. Cheers.

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Old 04-21-2015, 06:04 PM   #4
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The file size is pretty much determined by bit rate. You get the same quality with lower bit rate using H.264 encoding (the most common one used in .mp4 files). If you're willing to accept smalller video format, you can get the same quality with lower bit rate (smaller file size) except that the video format figures into your overall perception of quality if it gets too small. You can improve the quality-vs-file-size tradeoff by devoting more processor time to the re-encoding process (Mpeg2-->H.264) but typically you might see only a 10% or 20% improvement at the expense of 2X the processing time.

In a nutshell, I suspect the .mp4 files produced by Tivo Desktop are probably about as good a you'll get if you're satisfied with their quality. You can duplicate, or possibly better, that with VideoReDo or Handbrake, but whether it would be worth your extra time and expense is another question. VideoReDo has the major advantage of allowing you to edit out commercials.

Your requirement is non-typical because you are willing to accept archiving with the reduced quality and format normally associated with mobile device video. I think many of us would question whether your are going to be happy with that in the long run. You can retain format and quality comparable to your TiVo recordings using H.264 re-encodes but with a size reduction of only about 30%. If you remove commercials you could reduce size to about 50% of the TiVo recording.

Once you firm up your strategy there is plenty of help on the details available here or on the VideoReDo or Handbrake forums.

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Old 04-22-2015, 07:34 AM   #5
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Quote:
Originally Posted by Scott9mm View Post
Thanks. I knew some of this (like mpeg2, decode, and VRD). While the iPad format in TiVo Desktop produces files comparable to basic analog in quality and size, it seems the TiVo transcodes that format when it transfers from a PC to the TiVo (at least using Desktop: the transfer is slow and the file grows by a factor of 5). The Streambaby Wiki page on code.google provides some compatibility clues but video coding and file format must be a complex subject.
Couple of things here. First, the reason the files grow when you transfer them back to the tivo with Tivo Desktop is because TD is quite outdated and does not know the Roamio can handle h.264 video natively. Suggest you switch to pytivo and kmttg rather than TD. The mp4 files will be transferred back without growing or further transcoding. One downside to the ipad profile is it encodes the audio to AAC stereo, losing any 5.1 surround tracks. It would be better to store the videos as mp4 with an AC3 track which the tivo takes natively.

Second, the streambaby archive you are looking at google code is very outdated. Check out the Streambaby thread in the Home Media section of this forum and have a look at the more recent versions.

http://www.tivocommunity.com/tivo-vb...d.php?t=416858

moyekj has taken Streambaby a long way.

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Old 04-22-2015, 01:19 PM   #6
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This explains a lot. Looks like there will be pyTivo in my future. I'm (slowly) experimenting with each of the Desktop Plus portable formats to see what kind of file they produce. I guess I'll do the same with kmttg and pyTivo at some point.

I still use an ancient (20+ year old) Sony stereo receiver but I think it's time for an upgrade. So maybe I will care about 5.1 sound. I'm currently having a ground loop problem that puts some 60hz hum into the audio (related to the cable connection) so maybe a new receiver with HDMI and/or fiber will fix that too.

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Old 04-22-2015, 04:05 PM   #7
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Try VideoReDo. You can open the .tivo file, edit out the commercials, and then save to H.264 .tivo file and it will likely reduce the file size by half.

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Old 04-23-2015, 01:27 AM   #8
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I just did a 5 minute SD recording test (56MB), converted to iPad MP4 with KMTTG and the resulting file is 94MB.

I thought the .MP4 file would be smaller, but its not the case.

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Old 04-23-2015, 07:50 AM   #9
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Quote:
Originally Posted by ThAbtO View Post
I just did a 5 minute SD recording test (56MB), converted to iPad MP4 with KMTTG and the resulting file is 94MB.

I thought the .MP4 file would be smaller, but its not the case.
You should check the dimensions of your video source (with mediainfo). Sounds like you went from 480x??? source to 1280x??? converted which would increase file size. The converted video dimensions should be equal or less than the source video.

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Old 04-23-2015, 09:09 AM   #10
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I just did a 5 minute SD recording test (56MB), converted to iPad MP4 with KMTTG and the resulting file is 94MB.

I thought the .MP4 file would be smaller, but its not the case.
That encoding profile uses x=1280 resolution, so you are doubling the horizontal resolution and increasing vertical resolution if starting from SD recordings so hardly surprising it will be bigger.

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Old 04-30-2015, 09:43 PM   #11
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By way of feedback: After many experiments, I decided to use the VGA portable format (MP4) in TiVo Desktop Plus to compress my archived TiVo files. The resulting files are slightly smaller than my old basic-quality-analog files and the resulting image quality is comparable if not better. I tried and liked kmttg, VideoReDo, and pyTivo but decided to keep it simple because I already have DTP running on the machine.

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