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  1. I use VLC on windows xp, and I can increase the playback speed up to 4x and it still has audio. But when I go to the next speed (8x) there is no audio.

    Is there a way, or another video software or something, to play a video back at 8x speed and still hear the audio?

    Thanks!
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  2. I'm a MEGA Super Moderator Baldrick's Avatar
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    Try mpchc, play->increase speed.
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  3. Thanks for the suggestion, however when I try to play them in mpchc all I get are still frames. I hit Play and it says Playing but I only see one frame with no sound (as if it is paused). So mpchc seems unable to play these files.

    The videos I am playing are large 12.0MBit/sec (CBR) MPEG2, so like 3 gigs for a half hour video. So presumably that's why mpchc can't play them. (But VLC plays them fine.)

    So I'm still looking for a solution.
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  4. Member
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    smplayer can, but you might be limited by CPU power
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  5. Member
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    Originally Posted by blud View Post
    Is there a way, or another video software or something, to play a video back at 8x speed and still hear the audio?
    With a lot of modern video codecs, realtime high-speed playback is going to be limited by your CPU.

    The "or something" option would be to pre-process the video - speed up then convert to one of the common framerates (25 or 29.97). Any decent video editor can do this, and you can speed up the video as much as you want without thrashing your CPU on playback.
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    See this thread for a solution using Avisynth:
    http://forum.videohelp.com/threads/344497-Best-method-for-time-lapse-video

    You wouldn't need to create a new video file - just 'play' the Avisynth script instead of the original video.
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    Originally Posted by Gavino View Post
    See this thread for a solution using Avisynth:
    http://forum.videohelp.com/threads/344497-Best-method-for-time-lapse-video

    You wouldn't need to create a new video file - just 'play' the Avisynth script instead of the original video.
    Wouldn't avisynth be limited by the speed it can decode the MPEG2 stream like any other media player?
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    Originally Posted by intracube View Post
    Wouldn't avisynth be limited by the speed it can decode the MPEG2 stream like any other media player?
    Possibly, depending on the exact nature of the problem.
    The solution is still viable, but it might need re-encoding if the script cannot be 'played' in real time.
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  9. Using AviSynth to play an NTSC DVD VOB at 8x took about 20 percent CPU usage on my Core i5 2500K. Of course, with AviSynth running a single thread that may be close to the limit for smooth playback.

    fast, high pitched audio:
    Code:
    DirectShowSource("VTS_02_3.VOB") 
    SelectEvery(8).AssumeFPS(30000,1001)
    ResampleAudio(6000).AssumeSampleRate(48000)
    fast but normal pitched audio:
    Code:
    DirectShowSource("VTS_02_3.VOB") 
    SelectEvery(8).AssumeFPS(30000,1001)
    TimeStretch(tempo=800)
    Last edited by jagabo; 4th May 2012 at 08:08.
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  10. Originally Posted by poisondeathray View Post
    smplayer can, but you might be limited by CPU power
    smplayer almost does it. It will play it up to 4x, but when I go up to 5x it occasionally loops the audio like a record skipping (even though the video doesn't loop), and beyond 5x it constantly skips and can't handle it.

    It's only taking 30% cpu, so it's not the cpu limiting it. I'm guessing it's maybe hard drive access that is limiting it. Regardless, it doesn't work.

    Also, the 4x audio sounds "choppy" in smplayer whereas in VLC is sounds 'normal'. I am reviewing VHS captures to check for audio and video problems (since some of the tapes were acting up, and if I find problem parts I can actually go back and re-record them and sometimes they play back fine the 2nd time for some odd reason). So, with the choppy audio and the skipping/looping, the 5x is no good. So far 4x in VLC is the best method I have.
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  11. Originally Posted by intracube View Post
    Originally Posted by blud View Post
    Is there a way, or another video software or something, to play a video back at 8x speed and still hear the audio?
    With a lot of modern video codecs, realtime high-speed playback is going to be limited by your CPU.

    The "or something" option would be to pre-process the video - speed up then convert to one of the common framerates (25 or 29.97). Any decent video editor can do this, and you can speed up the video as much as you want without thrashing your CPU on playback.
    If I understand you correctly you mean that I should open the videos in an editor, apply a filter (or whatever) to speed up the video, and then render out the video.

    That would be a good idea if the goal was to create fast videos for playback later. But I'm just trying to review a bunch of vhs captures. The only reason I want to view at greater than 4x (with sound) is so it takes less time for me to check over the videos (to look for problems that would require me re-capturing since these tapes (or vcr?) are problematic in areas. So, with your suggestion, the added time for editing and rendering would negate the whole point.
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  12. Originally Posted by jagabo View Post
    Using AviSynth to play an NTSC DVD VOB at 8x took about 20 percent CPU usage on my Core i5 2500K. Of course, with AviSynth running a single thread that may be close to the limit for smooth playback.

    fast, high pitched audio:
    Code:
    DirectShowSource("VTS_02_3.VOB") 
    SelectEvery(8).AssumeFPS(30000,1001)
    ResampleAudio(6000).AssumeSampleRate(48000)
    fast but normal pitched audio:
    Code:
    DirectShowSource("VTS_02_3.VOB") 
    SelectEvery(8).AssumeFPS(30000,1001)
    TimeStretch(tempo=800)
    I downloaded AviSynth, and created a script file in the same folder as the video file:

    DirectShowSource("myvideo.mpg")
    SelectEvery(8).AssumeFPS(30000,1001)
    TimeStretch(tempo=800)

    I then opened that avs script file (as a video) in VirtualDubMod. Upon doing so, VirtualDub gives me a warning box saying:

    "Couldn't locate decompressor for format "YV12" (unknown).
    VirtualDub requires a Video for Windows (VFW) compatible codec to decompress
    video. DirectShow codecs, such as those used by Windows Media Player, are not
    suitable. Only "Direct stream copy' is available for this video."

    Then if I hit play vdub crashes.

    Can I make this work?
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  13. Originally Posted by blud View Post
    Couldn't locate decompressor for format "YV12" (unknown)...
    ffdshow includes a YV12 "decoder". Start -> All Programs -> ffdshow -> Video Decoder Configuration...

    Name:  yv12.jpg
Views: 600
Size:  74.7 KB
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  14. Originally Posted by blud View Post
    It's only taking 30% cpu, so it's not the cpu limiting it.
    Not necessarily. If you're running a quad core CPU and the program is single threaded it may only be able to use ~25 percent of the CPU. And when a media player gets behind, it will often try to skip forward requiring a disk seek to the next key frame. That will cause CPU usage to drop while it waits for disk I/O to complete.
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    Originally Posted by blud View Post
    If I understand you correctly you mean that I should open the videos in an editor, apply a filter (or whatever) to speed up the video, and then render out the video.
    That's right.

    That would be a good idea if the goal was to create fast videos for playback later. But I'm just trying to review a bunch of vhs captures. The only reason I want to view at greater than 4x (with sound) is so it takes less time for me to check over the videos (to look for problems that would require me re-capturing since these tapes (or vcr?) are problematic in areas. So, with your suggestion, the added time for editing and rendering would negate the whole point.
    If you're trying to limit the time spent in front of the computer, you could automate the conversion process with a script - leave it to run overnight and review the videos the next day.

    The downside to this is you'd be throwing away 7 out of every 8 frames and might miss the very glitches you're trying to spot...
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  16. Originally Posted by jagabo View Post
    Originally Posted by blud View Post
    Couldn't locate decompressor for format "YV12" (unknown)...
    ffdshow includes a YV12 "decoder". Start -> All Programs -> ffdshow -> Video Decoder Configuration...
    So are you saying I need to install ffdshow? (I'm confused why you show that picture.)
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  17. Originally Posted by jagabo View Post
    Originally Posted by blud View Post
    It's only taking 30% cpu, so it's not the cpu limiting it.
    Not necessarily. If you're running a quad core CPU and the program is single threaded it may only be able to use ~25 percent of the CPU. And when a media player gets behind, it will often try to skip forward requiring a disk seek to the next key frame. That will cause CPU usage to drop while it waits for disk I/O to complete.
    I'm running dual core and the program is multi-threaded. I can see on the task manager chart that the cpu usage doesn't exceed something around 60% on either core, yet at a certain playback speed, the audio decides to start looping/skipping. So I can only assume that it's not the cpu limit, because you would expect to see those cpu usage charts going close to the top before you would say it's the cpu limit causing the problem.

    Either way, we are both saying that the end problem seems to be disk I/O lag. (Which is certainly the worse bottle neck on this machine since I don't have solid state drives.)
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  18. Originally Posted by intracube View Post
    If you're trying to limit the time spent in front of the computer, you could automate the conversion process with a script - leave it to run overnight and review the videos the next day.
    This is true, however I am also trying to limit the time in which the computer is being hogged by video processes, and limit the total calendar time to finish this stuff. Just installing the tools, figuring out how to process the videos etc would probably take hours :P (Would be better if I was already set up of course.) The conversion would probably take several nights, and besides, I don't really want to leave the computer on overnight because of heat issues and that the computer is in my bedroom hehe.

    Originally Posted by intracube View Post
    The downside to this is you'd be throwing away 7 out of every 8 frames and might miss the very glitches you're trying to spot...
    The type of glitches I am trying to spot would most likely be seen even with 7 out of every 8 frames cut. Like, the vcr would go to a blue screen for a half a second or so, or the audio would go like BRUUPPPBRUPPPP loudly.

    With VLC, I can watch at 4x, and then if I notice anything, I can immediately pause, go back, and reduce the speed to 2x or 1x to really see how bad the glitch is. Obviously with a re-encoded video missing 7 out of every 8 frames I couldn't do that, although I suppose I could look at time codes and then go watch the original video. If I had many more videos than I do (I do have a bunch though) then I would seriously consider this method though.

    I'm just kind of bummed, because if VLC would simply have audio at 8x, then problem solved, but VLC auto-mutes it. Perhaps there is a way to tell VLC to have audio at 8x?
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  19. Originally Posted by blud View Post
    I'm running dual core and the program is multi-threaded.
    How do you know? And how do you know there's not one stage in the pipeline that isn't multithreaded? Just because both graphs in Task Manager show CPU usage doesn't mean there are two threads running. Windows will usually bounce a single thread back and forth between both (or more) cores. But that single thread will only ever be running on one core at a time. (The switching will be happening in very small time increments, much too small to show up in Task Mangager.) So on a dual core system a single thread will never consume more than 50 percent of the CPU. On a quad core system never more than 25 percent. Etc.

    Playing media files is usually broken into more than one thread but a part of the pipeline (read file, split audio and video streams, decompress streams, render streams) could still be single threaded and a bottleneck.

    Originally Posted by blud View Post
    Either way, we are both saying that the end problem seems to be disk I/O lag.
    Not really. In the case I outlined disk I/O only becomes a problem because the CPU couldn't keep up in the first place. Consider an 8 Mb/s DVD MPEG 2 file. That's 1 MB/s of data transfer rate, only 8 MB/s at 8x. Any hard drive made in the last 10 years can sustain that. If you're playing DV AVI (3.6 MB/s) files, losslessly compressed, or uncompressed files, disk I/O is more likely to be a problem.
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    Originally Posted by blud View Post
    The type of glitches I am trying to spot would most likely be seen even with 7 out of every 8 frames cut. Like, the vcr would go to a blue screen for a half a second or so, or the audio would go like BRUUPPPBRUPPPP loudly.
    Is the audio always affected when you get these glitches? If the audio goes wrong in an obvious way (silence or static) you might be able to spot the errors just by looking at the audio waveform:
    Name:  waveform_errors.jpg
Views: 617
Size:  14.4 KB

    ...not that it matters, but I originally missed where you said the videos were MPEG2... and MPEG2 certainly isn't a 'modern codec'... But I'm still not surprised that you're having problems trying to play at these speeds.
    Last edited by intracube; 5th May 2012 at 00:24.
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  21. Originally Posted by jagabo View Post
    Originally Posted by blud View Post
    I'm running dual core and the program is multi-threaded.
    How do you know? And how do you know there's not one stage in the pipeline that isn't multithreaded? Just because both graphs in Task Manager show CPU usage doesn't mean there are two threads running. Windows will usually bounce a single thread back and forth between both (or more) cores. But that single thread will only ever be running on one core at a time. (The switching will be happening in very small time increments, much too small to show up in Task Mangager.) So on a dual core system a single thread will never consume more than 50 percent of the CPU. On a quad core system never more than 25 percent. Etc.
    Yeah, I merely assumed it was multi-threaded because of what the chart showed. But it is now apparent that it is extremely likely you are right. In mplayer, the CPU can handle playing the *video* portion of the video at 8x, but not the audio. And then it chokes and probably has I/O problems. But, considering what you say about the cpu, it may be purely a cpu issue and not even causing a further i/o problem.

    So it is highly likely that even if I could get VLC to have audio at 8x, or use some other program that can do 8x audio like mplayer, no solution would work; 4x is the max this system can do.
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  22. Originally Posted by intracube View Post
    Originally Posted by blud View Post
    The type of glitches I am trying to spot would most likely be seen even with 7 out of every 8 frames cut. Like, the vcr would go to a blue screen for a half a second or so, or the audio would go like BRUUPPPBRUPPPP loudly.
    Is the audio always affected when you get these glitches? If the audio goes wrong in an obvious way (silence or static) you might be able to spot the errors just by looking at the audio waveform:
    Attachment 12316

    ...not that it matters, but I originally missed where you said the videos were MPEG2... and MPEG2 certainly isn't a 'modern codec'... But I'm still not surprised that you're having problems trying to play at these speeds.
    No, unfortunately the potential audio issues are probably too random for that. (sometimes quiet, sometimes loud static). I mean, I could probably find a bunch of it that way, but, I don't even think Vegas can load these files and if it could they would probably be all slow and annoying. (Vegas being the only app I have where I could see those wave forms.)


    So it looks like the solution to my original post is: Yes, there is a way to play videos (with audio) at 8x: Smplayer. But only if your cpu is fast enough to do it. (and mine isn't)


    Thanks for the help
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  23. Originally Posted by blud View Post
    Yes, there is a way to play videos (with audio) at 8x: Smplayer. But only if your cpu is fast enough to do it. (and mine isn't)
    What CPU are you running?

    I don't know anything about the player you're using. But if it has any A/V filtering options turn them off to reduce CPU load.

    Also try PotPlayer. It allows up to 12x speedup. It played a DVD VOB file smoothly at 12x on my i5 2500K.
    Last edited by jagabo; 5th May 2012 at 08:07.
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  24. Just amd dual core 2.2 ghz. Pretty old now.
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