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| | |-+  mpegplayer A/V sync - please report experiences
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Author Topic: mpegplayer A/V sync - please report experiences  (Read 29623 times)

Offline linuxstb

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mpegplayer A/V sync - please report experiences
« on: March 26, 2007, 02:41:09 PM »
I've just committed some improvements to the A/V sync in mpegplayer.  It seems to be working for my streams, but it would be useful to get feedback (good or bad) from more people.

Note that for mpegplayer to even attempt to play a video in sync with the audio, you MUST enable both the Limit FPS and Skip Frames options in mpegplayer.

Also, before reporting any problems, please test the video on a desktop video player and make sure it is playing in sync there - to rule out any encoding issues.
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Offline Mad Cow

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Re: mpegplayer A/V sync - please report experiences
« Reply #1 on: March 26, 2007, 04:41:25 PM »
Video and audio were in sync for me right after the first commit, so I can't comment on this one. :P
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iRiver H10 5GB, Gigabeat F40, Gigabeat S60, all rockboxed. :P

Offline Nate!

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Re: mpegplayer A/V sync - please report experiences
« Reply #2 on: March 26, 2007, 07:09:43 PM »
Worked for me after the first sync also.  Although, I probably should test on a movie that's filmed in my native language.  Watching House of Flying daggers with english voice over probably isn't a good idea.  ;D Just Joking around.  I'll try with an updated build and appropriate movie.  ;)
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Offline mannequin

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Re: mpegplayer A/V sync - please report experiences
« Reply #3 on: March 26, 2007, 11:05:14 PM »
all the videos that had slight sync problems before the improvements are perfectly OK for me now. again, thanks a lot, linuxstb. it's truly amazing seeing the gigabeat kicking the video.
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Offline pabouk

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Re: mpegplayer A/V sync - please report experiences
« Reply #4 on: March 27, 2007, 11:45:49 AM »
On iriver H120 the picture is slower than the sound. After one minute of playback the picture was several seconds behind the sound. Tested on Elephants Dream, 176x128-310kbps.

BTW: The framerate on H120 is terribly low :( Maybe it would be worth to try spatial instead of time dithering for the levels of grey.
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Offline ColdSphinx

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Re: mpegplayer A/V sync - please report experiences
« Reply #5 on: March 27, 2007, 12:45:00 PM »
Do you have skipframes enabled?
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Rockbox.src

Offline devonian69

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Re: mpegplayer A/V sync - please report experiences
« Reply #6 on: March 27, 2007, 03:21:56 PM »
I ripped one of my Seinfeld DVDs into an mpeg file and it worked great! I was very impressed with the sync. I honestly had to keep reminding myself to pay attention for it - otherwise I would never have even thought about it.

I am using a Gigabeat F10
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Offline Soader03

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Re: mpegplayer A/V sync - please report experiences
« Reply #7 on: March 27, 2007, 04:02:26 PM »
The video is about 1-2 seconds faster than the sound. I have all the options enabled. I use a Gigabeat F10.
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Offline Llorean

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Re: mpegplayer A/V sync - please report experiences
« Reply #8 on: March 27, 2007, 04:03:35 PM »
"1-2 seconds faster" meaning it plays 1-2 seconds ahead of the sound all the way through?

And what SVN revision is this with?
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Offline linuxstb

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Re: mpegplayer A/V sync - please report experiences
« Reply #9 on: March 27, 2007, 04:05:17 PM »
Quote from: Soader03 on March 27, 2007, 04:02:26 PM

The video is about 1-2 seconds faster than the sound. I have all the options enabled. I use a Gigabeat F10.


If that happens with current SVN, and the file plays perfectly on your computer, can you upload the file somewhere for me to analyse?
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Offline Soader03

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Re: mpegplayer A/V sync - please report experiences
« Reply #10 on: March 27, 2007, 04:09:18 PM »
Um, ok. I'll do an update and try a file. I'll edit this post for the uploaded video.

**EDIT**

http://www.megaupload.com/?d=LSQPSWR0
Well done, the video is here, sorry if it's at Megaupload and it's slow...
Check the guy with the yellow t-shirt signing.

**REEDIT**

I just want to add that this video was synchronized before the synchronization update.
« Last Edit: March 27, 2007, 04:41:09 PM by Soader03 »
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Offline linuxstb

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Re: mpegplayer A/V sync - please report experiences
« Reply #11 on: March 28, 2007, 03:30:23 AM »
Thanks for uploading that file.

It's not easy to tell what the correct a/v sync should be on that video, but comparing mpegplayer with "mplayer" (the video player I use for reference), there is definitely a large difference, so something is wrong with mpegplayer.

Before the AV sync commits, Rockbox would just play the video and audio at the correct speeds without taking into account the timestamps in the file.  mpegplayer now attempts to play the video and audio according to those timestamps, which is where it must be going wrong in your file.

If you (or anyone else) have other videos with similar problems, they would be useful to have as well.
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Offline pabouk

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Re: mpegplayer A/V sync - please report experiences
« Reply #12 on: March 28, 2007, 04:09:24 AM »
Quote from: ColdSphinx on March 27, 2007, 12:45:00 PM

Do you have skipframes enabled?

Yes, linuxstb described it as a requirement for this test and I think that it is obvious.

In addition the "Show FPS" option does not work on H120. Is it supposed to work on greyscale targets?
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Offline Llorean

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Re: mpegplayer A/V sync - please report experiences
« Reply #13 on: March 28, 2007, 04:13:01 AM »
No, due to the way the grayscale library works it won't display.
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Offline Didro

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Re: mpegplayer A/V sync - please report experiences
« Reply #14 on: March 28, 2007, 04:15:00 AM »
Have to say that before improvements my quality of video in MpegPlayer on IPOD nano was perfect and A/V sync works wonderfully. But after this it became worse, especially video. So please do feedback.
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iPOD Nano 1gen 4GB Black

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