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Old 03-04-2009, 06:01 PM   #271
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Originally Posted by moyekj View Post
OK, I found a tivoapp 11.0b binary and interestingly enough "strings" command does find avcL41MP4 among other strings containing mp4.
Can you open the binary in a hex editor and see if you can find any other strings around the vc1ApL3 and avcL41MP4 strings which might be of interest? Maybe they support some other format that we don't know about yet

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Old 03-04-2009, 06:09 PM   #272
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Can you open the binary in a hex editor and see if you can find any other strings around the vc1ApL3 and avcL41MP4 strings which might be of interest? Maybe they support some other format that we don't know about yet

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The full list appears to be:
tivo, windowsMedia, mpeg2ProgramStream, mpeg2TransportStream, avcL41MP4, vc1ApL3

hmm. auto pushes of mpeg2 transport streams would be interesting...

P.S. Around that vicinity there are also some copy protection (CCI byte) related strings like:
copyFreely, copyNever, copyNoMore, copyOnce, none
Maybe there is hope to turn off copy protection when these are auto-pushed to Tivos...

wmcbrine's idea of searching through tivoapp binary looks like has opened up a bunch of mini-projects to explore new capabilities. Good stuff.
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Old 03-04-2009, 08:20 PM   #273
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Originally Posted by moyekj View Post
The full list appears to be:
tivo, windowsMedia, mpeg2ProgramStream, mpeg2TransportStream, avcL41MP4, vc1ApL3
There are two lists -- the first one, just after "supportedEncodingType", has only avcL41MP4, vc1ApL3 and mpeg2ProgramStream. I think those are the only valid ones... at least, "windowsMedia" doesn't work.

Quote:
P.S. Around that vicinity there are also some copy protection (CCI byte) related strings like: copyFreely, copyNever, copyNoMore, copyOnce
Yeah, those look like the right values, but what's the key name? I figured it was "cgms", but that gets rejected, and I don't see any other likely candidates around there.

Quote:
Originally Posted by Dan203
Perhaps the dual request has something to do with DRM.
I don't think that's it. The last time I tried, it actually took three requests. And one time, it went on the first try (just after I'd switched to video/bif, which is why I'd thought that was the fix). All with the same test file.

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Could the MIME type also be why pull mode doesn't work with these new formats?
I'm pretty sure I tested that unsuccessfully already, but that might've been before I realized that no MIME type was being sent at the start of a file, so I'll check again.

Edit: Yeah, reconfirming that it doesn't work.
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Old 03-05-2009, 03:37 PM   #274
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I confirmed last night that Tivo can't decode 5.1/7.1 channel WMA3 audio. So looks like still only VC-1 AP (<= L3) video and 2 channel CBR WMA2 audio is supported as documented in the Wiki page.
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Old 03-05-2009, 07:39 PM   #275
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moyekj, can you try this clip?

http://forum.videohelp.com/images/guides/p1872213/wvc1%20+%205.1ac3.asf

It's converted from one of Apple's Dark Knight trailers. VC-1 video and AC3 5.1 audio in an ASF container. VLC seems to handle it fine on Windows.

Found it in this thread:

http://www.videohelp.com/forum/archi...d-t354346.html

If that works, I might be able to rip a bunch of my old HD DVDs and just toss them at the Tivo. Would have to transcode the audio from EAC3 to AC3, but that shouldn't be too bad. Albeit they'd be rather huge files...
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Old 03-05-2009, 08:03 PM   #276
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I can try it but I doubt it will work. I already tried asf container with VC-1 video and AC3 audio (and AAC audio) and it didnt' work. If you convert to wma2 CBR 2 channel audio then it probably would work...
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Old 03-05-2009, 08:07 PM   #277
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Ah, nevermind then.
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Old 03-05-2009, 08:22 PM   #278
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Confirmed. With AC3 audio the Tivo won't actually reject it for either streaming or pushing, but when you go play it will actually buffer on the Tivo but you get no video and super fast playback. WMA2 CBR 2 channel audio is required by the looks of it for now...

NOTE: After converting that clip's audio to WMA2 with ffmpeg it then did work:
ffmpeg.exe -i wvc1_51ac3.wmv -vcodec copy -acodec wmav2 -ac 2 -f asf test.wmv
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Old 03-23-2009, 11:40 AM   #279
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Just a quick note to say I finally updated the Windows installer for wmcbrine's pyTivo fork over the weekend.

New version pyTivo-wmcbrine-2009.03.19-RC1 uses his near latest code with MP4 & WMV non-transcode Push, better Push metadata, and fixed web config browser compatibility.

On my side of things this new installer should play nicer on Vista (it avoids writing anything to the pyTivo program folder during runtime) and the Python detection issues for 64 bit OSes should be fixed.

NOTE: Because we moved a lot of things around, you should UNINSTALL past versions AND start over with the installer's freshly generated conf file (in the new conf location) and re-customize rather than reusing your old conf.

Download from:

http://pytivo.krkeegan.com/updated-w...3-21-t512.html
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Old 03-23-2009, 01:01 PM   #280
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New version pyTivo-wmcbrine-2009.03.19-RC1 uses his near latest code
You probably should update again.
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Old 03-23-2009, 02:23 PM   #281
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You probably should update again.
Hey, I said "near" didn't I

I need to figure out how to script a few things on my end to make updating easier. The NSI builder script is somewhat painful to update when files are added or removed (like with the mutagen and eyeD3 stuff.) Synching changes to existing stuff isn't so bad. But you change stuff like hourly
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Old 03-26-2009, 02:56 PM   #282
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OK, this isn't directly TiVo related, but it seems relevant: Is there a way to transcode only the audio portion of a MP4 file, leaving the video unmodified? I have an MP4 that was transcoded by Handbrake that has AC3 audio. I'd like it to have AAC audio instead; is there a way with Handbrake (or anything else, for that matter) to do this conversion?

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Old 03-26-2009, 03:33 PM   #283
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OK, this isn't directly TiVo related, but it seems relevant: Is there a way to transcode only the audio portion of a MP4 file, leaving the video unmodified? I have an MP4 that was transcoded by Handbrake that has AC3 audio. I'd like it to have AAC audio instead; is there a way with Handbrake (or anything else, for that matter) to do this conversion?

Brad
Something like this with ffmpeg may work:
ffmpeg -i INPUT.mp4 -vcodec copy -copyts -acodec libfaac -f mp4 OUTPUT.mp4
(This will only re-encode audio)

With the handbrake GUI you could do it by using your MP4 as source, but that will re-encode both video and audio thus losing quality and taking a long time.
Not sure if there is a way to do it with handbrakeCLI (the command line executable that handbrake calls).
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Old 03-26-2009, 05:04 PM   #284
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Thank you very much, moyekj! The conversion took only a few minutes and I'm ten minutes into watching it and there are no sync issues or anything else funky as yet.

Awesome!

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Old 04-04-2009, 12:15 PM   #285
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How can I tell if a Tivo recording is in Mp4? All my HD recordings are about 6GB/hr. Does this mean they are all mpeg2?
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Old 04-04-2009, 01:09 PM   #286
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The TiVo doesn't (yet) make MP4 recordings. Only material transferred over the network can be in MP4; and, so far, all of it is marked as copy prohibited on the TiVo, so you can't extract it back to a .TiVo file. There doesn't seem to be any indication on the info screens, either.
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Old 04-04-2009, 01:20 PM   #287
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OK, thanks. I misunderstood which direction these transfers were going.
Are all TivoHD recordings in MPEG2? Do cable companies have plans to broadcast other codecs?
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Old 04-04-2009, 02:49 PM   #288
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OK, thanks. I misunderstood which direction these transfers were going.
Are all TivoHD recordings in MPEG2? Do cable companies have plans to broadcast other codecs?
The TiVoHD records the videos stream as sent by the cable company. All cable companies currently use MPEG2. Many do have plans for MPEG4 at some point in the future, but nothing that's been formally announced.
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Old 04-06-2009, 05:18 PM   #289
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OK, thanks. I misunderstood which direction these transfers were going.
Are all TivoHD recordings in MPEG2? Do cable companies have plans to broadcast other codecs?
It's going to be a while-you need the whole pipeline to be upgraded (new set top boxes, switches, etc). Also, for reasons that would take a while to explain, the benefits of H.264 encoding are not as great for transmitted cable signals as they are for "local" video, so the benefits are going to only be moderate.

For now, you'll mostly see H.264 for satellite systems, where the simpler infrastructure (satellite to dish) makes it easier to upgrade.
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Old 04-06-2009, 07:12 PM   #290
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Also, for reasons that would take a while to explain, the benefits of H.264 encoding are not as great for transmitted cable signals as they are for "local" video, so the benefits are going to only be moderate.
I'd like to hear the explanation as to why this would be if you have time. I'm in the video industry (see sig) and have a good understanding of local TS streams so feel free to get technical. Is this a QAM issue? Or maybe since the cable companies would have to encode to H.264 on the fly they can't use some of the more advanced features of the codec that make it so efficient?

Just curious

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Old 04-06-2009, 10:12 PM   #291
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Well, I should clarify-a "locally" stored TS file streamed from the cable system would still have the same compression characteristics.

My basic understanding is that one of the main benefits of h.264 over mpeg-2 for say, a blu-ray disc is the lower number of keyframes. However, because of greater potential for lost packets and/or the need to keep channel change delay lower, h.264 transport streams used for satellite and cable have a higher number of keyframes and accordingly don't quite get as much extra benefit.



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I'd like to hear the explanation as to why this would be if you have time. I'm in the video industry (see sig) and have a good understanding of local TS streams so feel free to get technical. Is this a QAM issue? Or maybe since the cable companies would have to encode to H.264 on the fly they can't use some of the more advanced features of the codec that make it so efficient?

Just curious

Dan

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Old 04-06-2009, 10:43 PM   #292
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My basic understanding is that one of the main benefits of h.264 over mpeg-2 for say, a blu-ray disc is the lower number of keyframes. However, because of greater potential for lost packets and/or the need to keep channel change delay lower, h.264 transport streams used for satellite and cable have a higher number of keyframes and accordingly don't quite get as much extra benefit.
I'm not sure that's correct. It really doesn't make any sense since packet loss is more of an issue when streaming programming from the Internet, yet h.264 works very well there and the file sizes are significantly smaller than MPEG-2.

Also some channels are being distributed natively in h.264, HBO for example. HBO currently broadcasts using h.264 encoding at 8 mbps. Satellite providers just pass this on as is to their customers. Cable companies must convert the HBO channels to MPEG-2 which results in a loss of quality.
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Old 04-07-2009, 09:03 AM   #293
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I'm not sure that's correct. It really doesn't make any sense since packet loss is more of an issue when streaming programming from the Internet, yet h.264 works very well there and the file sizes are significantly smaller than MPEG-2.
All internet streaming I've seen buffers a significant portion of the video before starting playback, so that there's time to re-fetch any dropped packets. With cable and even more for satellite, there's not enough time (and the infrastructure isn't there) to replace any dropped packets.
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Old 04-07-2009, 10:31 AM   #294
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I'm not sure that's correct. It really doesn't make any sense since packet loss is more of an issue when streaming programming from the Internet, yet h.264 works very well there and the file sizes are significantly smaller than MPEG-2.
My understanding of this is imperfect, but I believe that Internet streams can be buffered to re-request missing packets, etc, whereas for cable/satellite transmissions, it's basically a single broadcasted stream that goes to everyone. The cable company is basically sending the same flow of packets to everyone simultaneously.

Re HBO broadcasting in H.264, it doesn't really matter whether HBO is doing it or the satellite provider-they know that it's being provided for broadcast, so they encode the stream with more keyframes. It's not that there's anything structurally different about the encoding, but at the encoding stage they know that it will be used for transmission, so they build it with more redundancy/less efficiency.

All that being said, this is far from my area of expertise, so if someone has a more informed understanding, I'll defer to them.
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Old 04-07-2009, 01:02 PM   #295
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All internet streaming I've seen buffers a significant portion of the video before starting playback, so that there's time to re-fetch any dropped packets. With cable and even more for satellite, there's not enough time (and the infrastructure isn't there) to replace any dropped packets.
Well that's where error correction kicks in.

Realistically though, there shouldn't be any packet loss on a cable system. Dropped packets would show up as macro-blocking on the TV since I'm pretty sure digital cable does not use TCP/IP, so there wouldn't be any way to re-fetch dropped packets.

Even if more key frames were needed, h.264 has some significant advantages over MPEG-2 which would still allow smaller bitrates without loss in quality.
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Old 04-07-2009, 03:29 PM   #296
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Most consumer H.264 encoders cap the GOP length at 50 frames. If cable companies used the same specs it would require up to 1.66 seconds to sync the stream and start decoding a channel change. That is a bit long, so I could see cable companies capping the GOP length at 25-30 frames to get it down to about 1 second.

However long GOPs are only part of the reason MPEG-4/H.264 is so efficient. Other things, such as the ability of B frames to reference multiple frames, variable macroblock sizes, multiple motion vectors and quarter pixel motion compensation can all still be used to lower the bitrate while retaining equivalent quality.

Like someone else pointed out above HBO uses an 8Mbps H.264 stream for transmission to providers. By contrast the major networks all use 15-18Mbps for the MPEG-2 HD streams. So by switching to H.264 cable companies could, at the very least, cram twice as many HD channels into their lineup.

I think the biggest problem is hardware. Most cable providers would have to upgrade a whole sloth of STBs and DVRs to support H.264, which would cost them some serious cash. There might also be some regulations due to the whole CableCARD thing. I don't H.264 decoding was ever part of CableCARD certification, so if the cable companies switched they'd limiting, or disabling, a lot of CableCARD enabled devices. Although they're still deploying SDV even though it breaks CableCARD, so maybe not.

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Old 04-11-2009, 11:33 PM   #297
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Is it possible to configure Pytivo to check for MP4 files and push in response to a pull request for one of those files?
I think this would be a very slick feature. Ideally, I'd like to see it as a special item when browsing a pyTivo share. For any folder that you browse into, pyTivo adds a special item as the first "file" called "[download this entire folder]". Selecting to transfer that item to the TiVo would trigger pyTivo to push all the individual files in there (while returning some dummy file to fulfill the pull request).

I'd love this for e.g. when returning from vacation and I put 10 short video clips from my digicam into a folder that pyTivo is sharing... then I wouldn't have to select to transfer each one, I could just click the [push all] option and wait a bit... then I'd get a folder called "My Vacation" (or whatever) on the TiVo that I could click Play on to see all and only those videos.
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