Playback not smooth. What's your favorite decoder ?

[nelis]

Hi,

I'm using right now the Hauppauge's Intervideo non-CSS decoder.

For recorded show the image quality is very good but the video is not always smooth ... Sometime it's like the video ignore some frames and play directly a later frame. The result is that video looks jerked. It's not catastrophic but it's visible.

For DVD, the video has the same issue but the sound is always jumping.

I suppose it's a decoder related issue.

Wich decoder are you using ? Wich one give the smoother video and the better image quality ?

Are there other settings that makes video smoother ?


My system is : Asus Pundit (Celeron 2.6GHz, 512Mb RAM), PVR 250, HD 200Gb

Thanks,

Nelis

[lonndoggie]

I was having the same problem, and what fixed it was installing ReClock.

A grossly simplified (and possibly inaccurate) explanation has to do with the fact that the MPEG-1 that is recorded by Sage is at 24fps, whilst your monitor is using something like 60fps, and keeping the two in sync is problematic. ReClock actually changes the speed of audio playback to effectively change the frame rate to equal what your video card is using (DirectShow syncs the video to the audio, which is The Right Thing To Do).

It's a subtle change--it's not like everyone is suddenly breathing helium, and more importantly, it works.

I seem to recall others here having some issues with getting ReClock to work, but it just up-n-worked for me after installing. I did fiddle with the parameters a bit, but just in a "that looks about right" kind of way, I didn't adjust them due to any problems I had.

Give it a try.

[stanger89]

FWIW:

When you play a file the playback speed is based on the audio clock, the video (29.97fps for Sage recordings, 23.97 for DVDs) ends up dropping frames to keep in sync with the audio. What reclock does is gets it's clock from the video card (so the video will play back right, no dropped frames) and then it resamples the audio to maintain sync.

[nelis]

I will try ReClock and WinDVD 6 (Is WinDVD 6 a good decoder ?). WIth these it should be ok, no ?

[salsbst]

...the MPEG-1 that is recorded by Sage is at 24fps..

I think PAL is 25 fps, NTSC is ~30 fps. Both are encoded as MPEG-2 by the card.

[nelis]

I have installed both ReClock and WinDVD 6.

The video with WinDVD 6 looks smoothy now (I have to check this on a long run video but seems ok now). But with ReClock I think I have a problem : The video and the sound are too slow ...... I'm in a PAL country, can someone give me the settings to make it work ?

My only issue left (I hope) is for DVD playing : the sound of the DVD become slow then fast then slow ... all the time. I tried the different audio renderers without success and in WinDVD itself I have the same problem. Any idea ?

[nelis]

Bad news : the video now is jerked again ...

I tried to play it directly in WinDVD and it looks OK but in SageTV it's jerked.

I tried with ReClock : in WinDVD, the clock in taskbar is green and it plays fine but in SageTV the clock is red or yellow and the video and sound are played two times slower than normal ...

And I still have the DVD problem. I can play it from WinDVD or SageTV I have the same result: the sound frequency changes all the time : it become higher then lower ...

I don't know what I can do now ....

[lonndoggie]

Here's a reply from someone else in another thread to someone having similar problems in a PAL locale and a suggestion they had:
------------
ekiwi
Well I have no idea what zoom player is trying to tell you but it seems confusing to me.
I suggest you add a PAL profile to the sage.properties file like the following

seeker/recording_qualities/PAL45VBR=PAL45VBR,384,48000,6000000

mmc/python2_encoding/ PAL45VBR=videobitrate=4500000|width=720|height=576
|audiobitrate=384|vbr=1|peakvideobitrate=6000000

Start SageTV and select PAL45VBR and record something.
Let me know what zoom player thinks of that file.


__________________
Ian Norman
ILN Multimedia - www.iln.com.au
-----------

Do some searching on ReClock and PAL around here...

Best,

Lonnie

PS--yes, 29.97 is the rate Sage records NTFS at, not 23.97, apparently that .03 between that and the video refresh rate is enough to cause the stutter now and then, and is small enough of a difference to allow ReClock to work its magic without noticeable problems. 25FPS vs 30FPS seems to be another story...

PPS--(specultative comment ahead) also, those who say reformat your hard drive to 64K blocks instead of the default 4K to solve this problem...while this is no doubt more efficient for large files, such as video files, I can playback HD transport stream files off a 4K-blocked disk without any skipping or stuttering, so if the smaller block size is a problem--for sage--it must lie in the video read buffering.

[Opus4]

Originally posted by lonndoggie
PPS--(specultative comment ahead) also, those who say reformat your hard drive to 64K blocks instead of the default 4K to solve this problem...while this is no doubt more efficient for large files, such as video files, I can playback HD transport stream files off a 4K-blocked disk without any skipping or stuttering, so if the smaller block size is a problem--for sage--it must lie in the video read buffering.

I believe I saw the math for this somewhere... When a video file on a 4K cluster partition is heavily fragmented, it can become impossible for the drive to seek to all the various clusters in time to read in the data stream fast enough to keep up with playback needs. 4K clusters will work just fine when not fragmented; it is when they become heavily fragmented that problems occur. That is why 64K clusters work better for recording/playback -- the drive does not need to seek as often to get to the next part of the file.

Edit: This would be especially true when recording & playing multiple streams simultaneously.

- Andy

[lonndoggie]

Originally posted by Opus4
I believe I saw the math for this somewhere... When a video file on a 4K cluster partition is heavily fragmented, it can become impossible for the drive to seek to all the various clusters in time to read in the data stream fast enough to keep up with playback needs. 4K clusters will work just fine when not fragmented; it is when they become heavily fragmented that problems occur. That is why 64K clusters work better for recording/playback -- the drive does not need to seek as often to get to the next part of the file.

Edit: This would be especially true when recording & playing multiple streams simultaneously.

- Andy

I'm sure that's all true, but when I've had stuttering problems, I've had a recently defragmented drive, I'm typically just playing back one stream--and, again, I can play back HD .ts files from that same drive without any such stutter.

Also--er, ah, I think--I've been able to play the stuttering files with other players sans stutter. So if it's the blocking, again, I think that'd directly related to the buffering algorithm used by the program opening and reading the file--likely Sage itself, I'd guess. Would probably be most efficient to pick the buffer sized based on disk block sizing, and read chunks of just that size, rather than trying to fill a single, large buffer with lots of disjoint blocks.

Maybe...

Many years ago I worked on a software MPEG decoder...buffering was a bette noir for me then, and I can't say I found the magic formula, either...