Is VDR _really_ the only solution to sync problems?

Discussion in 'TiVo Home Media Features & TiVoToGo' started by schmibble, Oct 31, 2011.

  1. schmibble

    schmibble New Member

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    After converting HD *.tivo files (from a series 4, if that matters) into *.mpg with DirectShowDump, I am tearing my hair out trying to edit them. Interestingly, my Tivo Desktop (non-plus) can't play the downloaded *.tivo files, but once I run them through DirectShowDump, media player can play them just fine--and they're in sync, no problems. But when I open them in an editor, they have nasty sync assymetries, and running them through PVAstrumento doesn't help (the result is unwatchable because of stutters).

    After spending a while searching for solutions, I came across this "known issue" from the kmttg "known issues" page (I haven't tried kmttg, so I lack prior familiarity with its documentation):

    "Encoding creates audio/video sync issues--Recordings originating from Tivos very often have timestamp defects that lead to problems if not corrected before encoding to other video formats. VideoRedo Quick Stream Fix is the only (non-free) tool out there that can reliably correct these defects such that when you encode the faulty recording to other formats it will be perfectly in sync."

    As a result of all this, I have two questions:

    1. It doesn't make sense to me that the DirectShowDump *.mpg's play back just fine but once I open them in an editor (whether Mpg2Cut2, CutAssistant with VirtualDub, or Avidemux--same result in all three), there are sync problems; and that PVAstrumento identifies sync problems so bad that it can't adequately fix them. Why in unholy cyberHades are the files synced in players but not in an editors?

    2. I thought maybe that if I coughed up the dough for Desktop Plus, which activates those hoidy-toidy MainConcept codecs, the sync problems would be solved. But if the kmttg site is correct, using Plus won't make any difference; only VideoRedo will do the trick. So is the kmttg assertion accurate? There's really nothing out there, including Desktop Plus, that will resolve this issue? It sticks in my craw to pay $50 for only a single feature in VDR to deal with something that is Tivo's fault and which they themselves should have fixed long ago. (One user, in post 8157811, says that kmttg+handbrake, set up a certain way, will encode to mp4 without sync problems, but he doesn't say whether he edits or not; if he doesn't edit, then I suspect that he's in the same boat as me, with converted files that play back fine in players but have sync problems in editors.)

    Thanks for any ideas.
     
  2. dlfl

    dlfl Cranky old novice

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    Why not test VideoReDo? You can use it free and uncrippled for a 15-day trial. Just download the version you want and in the menu system find the register for free trial function.

    One potential issue: VideoReDo's official release versions are frequently way out of date. They freely distribute the true updated ("Beta") versions on their forum. However I'm not sure how these beta versions interact with the free 15-day trial licenses. I would try the official release first. If it works, you don't need to worry about the beta version.

    By the way, there does seem to be a consensus about the unique powers of VRD's Quick Stream Fix to fix timestamp errors.
     
  3. moyekj

    moyekj Well-Known Member

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    That's because decoders are very forgiving of timestamp errors and other problems with encodings. However as soon as you are encoding to other formats these issues become a big deal. Some encoders deal with certain issues differently/better than others and it has been reported that handbrake can keep sync better than ffmpeg in some cases when the original mpeg has such glitches, but there really is no guarantee. VRD is the only solution that has worked for me and many others and if you do a lot of editing/encoding the $50 for VRD Plus is a small price to pay to fix the problems. The best thing is you can try the trial version for free to really see if it fixes the problem for you before ponying up the money.
     
  4. schmibble

    schmibble New Member

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    Thanks, moyekj. That both answers my question and explains why Tivo can afford to take such a cavalier attitude toward the sync issue. All right, I'll grit my teeth and do V-redo.
     
  5. Dan203

    Dan203 Super Moderator Staff Member TCF Club

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    Trial keys work fine with beta releases.

    schmibble - If you have any trouble with VideoReDo don't hesitate to ask me directly.

    Dan
     
  6. Nov 4, 2011 #6 of 12
    jalind

    jalind John

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    I don't believe this is TiVo. All the box does is wrap the mpeg2 transport stream into its TiVo wrapper as-is without doing any real transcoding. It's the broadcasters who create the HD transport streams and - likely even more problematic - the cable companies trying to shoehorn as much "HD" content into their bandwidth limited coaxial cable with as much compression as they think they can get away with; compare OTA with same program from cable frame by frame some time. It's dramatic - I call it "horrid definition" - and broadcasters are also severely compressing some programming, live sports is one very noticeable example. I've little doubt the TS timestamping problem, and the audio sync issue it creates, is a direct result of this.

    Furthermore the BCs and cable providers have zero motive to clean it up as long as it "plays" reasonably in sync. That someone might want to record and archive programs is not their problem, indeed anything that hampers this serves their content DRM and protection interest. My cable company is doing added compression of the transport streams, but no further transcoding that I can discern. Content differs between channels depending on how the cable company receives it. Some are 720p, supposedly 59.94 fps and some are 1080i allegedly at 29.97 fps. In reality I've found the mpeg2 frame rates vary within the stream and that 1080i is often a mix of interlaced and progressive. Not certain about 3:2 pull down for telecine of cinema but would not be surprised if that's sloppy too.

    As already cited, decoders are much more robust to this in realtime playback for display on a screen, but the sloppy timestamping with varying frame rates and mix of interlaced containing some progressive frames completely fouls up some encoders. It results in stuttering video and/or audio gradually slipping out of sync. I, like others, have found VideoRedo marvelous for editing TiVo HD recordings from cable without creating sync problems or stuttering video. It's also been able to repair stuttering video in many mpeg2s after a simple transcode with another tool like NeroVision has induced it (yes, even with Smart Encoding doing as-is frame copying). Doesn't help with creating Blu-Ray discs though as NeroVision frequently regenerates choppy stuttering video from 1080i recordings even with its Smart Encoding being used.

    I've had good results with maintaining 720p as 720p at 59.94 fps, and 1280x720 59.94 fps progressive mpeg2 is a legit Blu-Ray format. Have also had good results transcoding some problematic 1080i/29.97 fps to 720p/59.94 fps, or to 1080p/23.976 fps. I'll take a 10 minute or so sample and try each to see which works best, the latter usually working very well with cinema (movies) that were originally shot at 24fps. Note that 1080p - progressive - at 23.976 fps is also a legit Blu-Ray mpeg2 format. None of these transcoding transformations take very long with a reasonable speed dual-core processor; no more than 2-3 hours for a 2-1/2 hour movie. I don't recommend transcoding the TiVo mpeg2 into H.264 AVC mp4 for 720p/60, 1080p/24 or 1080i/30 Blu-Ray for practical reasons. While H.264 AVC is a superior compression scheme that can pack greater resolution into smaller storage space, it's also much more computationally complex, which means it can take days to transcode a 1080i/29.97 mpeg2 into a 1080i/29.97 H.264 AVC mp4 versus taking a few hours to transcode into a comparable mpeg2. OTOH, transcoding to an appropriate H.264 (there are at least 10 "flavors" of H.264) for devices like an iPod Touch, an iPhone or even an iPad is another matter, and usually doesn't take all that long as the output is much smaller resolution for a portable device screen versus HD resolution Blu-Ray.

    Finding some strategies that worked for me was quite time consuming and frustrating. YMMV with specific versions of Nero. I have 8 and 10, and the transcoding codecs in them are different. Fortunately I can also have both versions installed simultaneously without problems. Sometimes I've found one better than the other for transcoding a specific recording to the same Blu-Ray format.

    John
     
  7. Nov 5, 2011 #7 of 12
    jcthorne

    jcthorne Well-Known Member

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    I was with you and agreed with most every thing you posted up to this point. With a current processor it certianly does NOT take DAYS to encode a 1080p24 h264 video from an mpg2 original. On my laptop with an I7 Quad core at 2.2Ghz which is by no means bleading edge, just corporate issue mainstream these days, 1080p24 video encodes in just a bit longer than real time. IE about 3 hrs for a 2 hr film. But then again, file size drops from 20+ GB to about 6 for nearly identicle video quality and a file that can push to tivo in MUCH faster than real time, usually only a few minutes.
     
  8. Nov 6, 2011 #8 of 12
    Dan203

    Dan203 Super Moderator Staff Member TCF Club

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    Yeah days is a bit dramatic. Even on my 4 year old 2.8GHz Core 2 Quad I can recode 1080i to H.264 in about double real time. (i.e. 1 hour of content takes about 2 hours to encode) And with the batch manager you can just setup a few things to encode over night while you're sleeping and they're done in the morning.

    Dan
     
  9. Nov 6, 2011 #9 of 12
    lrhorer

    lrhorer Active Member

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    Absolutely, and simple transcoding doesn't take that long, either. On my old 3.0 GHz AMD 64 x 2 server, transcoding a two hour 1080i MPEG2 file only takes about 30 minutes. A full recode to h.264 takes about ten hours. On my 2.8 GHz AMD 64 x 6, it takes a little more than 2 hours.
     
  10. jalind

    jalind John

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    What are you using to do the transcoding? My efforts at AVC transcoding have met with outrageous times required using a 3.3 GHz AMD x6 1100T.

    In further experiments, EncoreHD in particular (movie channel on cable) streams all their movies in 1080i at 29.97fps, apparently using a telecine pulldown scheme to get 30fps from 24fps cinema. Causes major video stuttering issues with NeroVision (in Nero 8 and 10) trying to maintain it in 1080i at 29.97 fps. I've come to the conclusion it's most likely an inability to maintain the telecine pulldown properly. Still experimenting some with 1080p at 23.976 fps and 720p at 59.4 fps. While the stuttering video does not occur with 1080p at 23.976 fps, audio gradually slips out of sync. By the end of a 2 hour movie it's rather noticeable. 720p at 59.94 fps also avoids stuttering video and keeps audio in sync. Would like to find a way to use 1080p @ 23.976 fps though. NeroVision is very finicky with allowing SmartEncoding to frame copy the video stream.
     
  11. jcthorne

    jcthorne Well-Known Member

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    I use meGUI with a dgindexNV plug in. meGUI uses x264 for the encode and aften for the ac3 encode. The indexer will automaticly analyze and de-telecine if necessary and end up with a 23.97 fps 1080p video if the source is film. Audio sync has not been a problem for some time in meGUI for proper recodes.
     
  12. lrhorer

    lrhorer Active Member

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    HAve you checked that all six cores are in use? Many applications don't make use of multiple cores.

    I have no problems with video from EncoreHD when transcoding to .mpg using either tivodecode under Linux or VRD under Windows. I also have no problems recoding to h.264 using VRD. As I stated before, a full recode does take much longer than a simple transcode, but even a recode to AVC should be possible at not quite real time on a 6 core processor, unless you are compressing a great deal. The default for VRD is about 70% or a reduction of about 30%.

    Out of curiosity, why?
     

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