Cmd Line MPEG4 Encoder - ffmpeg

[Bubster]

Originally posted by Muchacho
I had it working well, but updated to Bubsters builds and set it up his way so I was using the same set up. Now I am havign audio sync issues- the video is like 1 second behind. I dont know what the problem is- I figured it had to do with -async so I set it up manually and still have the issue. Here is the settings file- Any ideas? Thanks for the help.

What happens if you enable the mp3 flag in the properties file?

It will use mp2 if that's not enabled. Which should work, but I haven't really used it in mp2 mode, so I can't say for certain.

[jcato]

Originally posted by Bubster
The first thing to try is running ffmpeg on its own, with a command line like the following on one of your MPGs in your Sage video dir:

ffmpeg -y -hq -i INFILE.mpg -f avi -b 1600 -vcodec mpeg4 -acodec mp3 -ab 128 -deinterlace -async 1 OUTFILE.avi

Replace INFILE with the name of one of your Sage MPGs, and OUTFILE with a name of your choosing.

- Neil.

Thanks! That line worked. The other one had the flag -s 640x480 and that seemed to be causing the problem. I disabled that and the program now it works.

Thanks again!

[Muchacho]

I changed it back to mp2 to see if I could fix it... I gives me the async problem both ways.

[Bubster]

Originally posted by Muchacho
I changed it back to mp2 to see if I could fix it... I gives me the async problem both ways.

Might be worth trying "-vsync 0"...

[Crim]

Okay I'll give the new file a try tomorrow since I'll sometime for it then.

[Muchacho]

Well I figured out that my audio synch issues are related to the recorded file. Sometimes it seems that when my HD has to turn on the first few seconds are a bit funny. This is not a problem for me usually b/c I usually have a decent padding. The mpg regains synch and plays fine, but the encoded mpeg4 is off. It doesent matter if async, vsync are on, or what codec I am using to encode video or sound. I guess if I edited out the initial problemed part it may work clean, but that sorta defets the purpose....

Also I have the audio drop out on long files. It is not always noticible on the -t 30 test either. Bubster if you want me to upload some of it to the ftp let me know. It doesent seem to be up or something.

I will keep trying things, but I am running out of ideas. Thanks for the hep!

[Bubster]

Originally posted by Muchacho
Well I figured out that my audio synch issues are related to the recorded file. Sometimes it seems that when my HD has to turn on the first few seconds are a bit funny. This is not a problem for me usually b/c I usually have a decent padding. The mpg regains synch and plays fine, but the encoded mpeg4 is off. It doesent matter if async, vsync are on, or what codec I am using to encode video or sound. I guess if I edited out the initial problemed part it may work clean, but that sorta defets the purpose....

Hmm. The -async flag in ffmpeg is for this exact purpose. Did you try it with "-async 1 -vsync 0" (i.e async on but vsync off)? AFAIK, you don't want both enabled at the same time, but one or the other.

Also I have the audio drop out on long files. It is not always noticible on the -t 30 test either. Bubster if you want me to upload some of it to the ftp let me know. It doesent seem to be up or something.

When you say it's not always noticable on the 30 sec test, do you mean the problem sometimes goes away when the output size is reduced, or that the audio dropout sometimes happens after 30 secs? If it's the latter, then people can always use -t 60 or whatever to ensure they reach the dropout point. The 30 was only chosen because people were getting dropouts at around the 10 second mark, so it seemed like a decent level of margin.

My ftp server failed to start when I rebooted it, but it's back up now. It would be good if you could upload a small test output with the audio dropout in it so other people can try it and see if it happens to them.

Also, if you can chop one of your Sage MPEG2 files down to a decent size (or do a very short recording or something), one which has the synch problem, and upload that as well, I can try it here, or even post it to the ffmpeg list and see if the maintainer can figure out why it isn't synching properly. If you're going to be uploading something pretty big, PM me and let me know so I don't reboot while you're uploading.

- Neil.

[Muchacho]

I will let you know when I have all the files ready to go- I have deleted them seeing as they were unwatchable. I will make sure that the problem still is there when I reduce the bitrate and resolution to make the files small.

[Muchacho]

I am uploading examples of the audio synch issue. I guess I should upload a segment of the origional mpg, but need to get a utility to cut it... I found a simple workaround if I use -ss to skip forward 30 sec (the messed up part of the video is only the first 10-20 sec) the audio synch is fine. It would be nice if I could fine a ffmpeg command to actually just start the encoding 30 sec into the file so that the initial part is just not there.

The audio dropout issue is odd- I having a hard time recreating it with short tests (ie t -60, t- 120). What is interesting is that the output file is like 5 seconds longer than the -t specified and those last 5 sec do not have sound. So it I make it -t 60 the audio drops out 5 sec before the end of the video, and if I do t -120 it looses sound 5 sec before the video. When I do the whole file it goes out at like 30 sec. Makes me wonder if I manually specified the -t to do the whole show, that it may work. I will let you know. Thanks

[Tej]

Originally posted by Muchacho
... It would be nice if I could fine a ffmpeg command to actually just start the encoding 30 sec into the file so that the initial part is just not there....

`-ss position'
seek to given time position. hh:mm:ss[.xxx] syntax is also supported.

[Muchacho]

I am noticing now that even if I fix the audio asynch in the beginning, it again looses synch later in the video. Odd thing is is that the same thing happens in autoGK. Makes me wonder if it has to do with my recording properties. I just have it set the the Best setting. What recoedign settings are you all using?

[JUC]

I just compressed a 3 gig file down to a 1.25 gigs but I lost audio after 5 seconds. This was a 1.5 hour show. This was the largest file I have compressed so far and all others have worked fine (they were all 30 minute shows). Any thoughts. I am using the current versions of the ffmpeg_compress.
thanks
JUC

[Crashless]

Originally posted by Muchacho
I am noticing now that even if I fix the audio asynch in the beginning, it again looses synch later in the video. Odd thing is is that the same thing happens in autoGK. Makes me wonder if it has to do with my recording properties. I just have it set the the Best setting. What recoedign settings are you all using?

How fast is your computer? Is the CPU usage maxed out? I have found on my laptop (PIII400) that I have to turn the playback quality slider all the way down in order to play full sized divx without the video going out of sync.

[Bubster]

Originally posted by JUC
I just compressed a 3 gig file down to a 1.25 gigs but I lost audio after 5 seconds. This was a 1.5 hour show. This was the largest file I have compressed so far and all others have worked fine (they were all 30 minute shows). Any thoughts. I am using the current versions of the ffmpeg_compress.
thanks
JUC

Can you compress the same file using the same parameters, but with "-t 30" (or 60), and see if that short clip still drops sound after 5 secs? If it does, can you upload it to my ftp server and I'll see if it works here?

- Neil.

[JUC]

Neil, I tried to insert the '-t 30' into the line posted below but I am unclear where it goes. You'll see where I put it but I couln't get ffmpeg_compressor to run with it where it is. Do I need to delete something? Here's the line:

<Value>ffmpeg -i @INPUT @QUALITY @SIZE -deinterlace -y -f -t 30 @OUTPUT_FORMAT @VSYNC -vcodec @VCODEC -b @VIDEO_RATE @ASYNC -acodec @ACODEC -ab @AUDIO_RATE @OUTPUT</Value>

Thanks
JUC

[Bubster]

Originally posted by JUC
Neil, I tried to insert the '-t 30' into the line posted below but I am unclear where it goes. You'll see where I put it but I couln't get ffmpeg_compressor to run with it where it is. Do I need to delete something? Here's the line:

<Value>ffmpeg -i @INPUT @QUALITY @SIZE -deinterlace -y -f -t 30 @OUTPUT_FORMAT @VSYNC -vcodec @VCODEC -b @VIDEO_RATE @ASYNC -acodec @ACODEC -ab @AUDIO_RATE @OUTPUT</Value>

Thanks
JUC

The "-f" and the "@OUTPUT_FORMAT" are tied together, so you can't put it between them. Just move the "-t 30" before the "-f" and you should be fine.

- Neil.

[JUC]

alright, I got the 30 second clip to work fine. I am now in the middle of compressing the original 1:30 minute show again to see if it works. I noticed that with the one that didn't work, the timeline only showed it being 1:11 (not 1:30). Well see...

[Muchacho]

Originally posted by Crashless
How fast is your computer? Is the CPU usage maxed out? I have found on my laptop (PIII400) that I have to turn the playback quality slider all the way down in order to play full sized divx without the video going out of sync.

1.6 GHz, I dont think it is the problem. It may be by MB which is one of the first athlon XP MB made or excesive HD fragmentation. I think I am going to try another MB and see what happens. I am pretty confident that the origional mpg file is currupt.

[JUC]

Well, I tried to compress my 1 hour and 30 minute file again hopeing that the audio woudln't drop out after 5 secs....But it did again!!! The 30 sec. clip worked fine however but the 1:30 clip drops out and is only showing up as 1:11 minutes? That seems a little odd. The original works great though. I think I will try compressing another file of around the same length and see what happens. Any help. Thanks
juc

[Bubster]

Originally posted by JUC
Well, I tried to compress my 1 hour and 30 minute file again hopeing that the audio woudln't drop out after 5 secs....But it did again!!! The 30 sec. clip worked fine however but the 1:30 clip drops out and is only showing up as 1:11 minutes? That seems a little odd. The original works great though. I think I will try compressing another file of around the same length and see what happens. Any help. Thanks
juc

OK, so when you compress the entire file, you get audio dropout after 5 secs. When you compress it with "-t 30", you get audio for the full 30 secs (or pretty close to it). Is that right?

Can you try the same movie with larger "-t" values (e.g. 300 might be a good test), to see if the dropout starts happening? It would be interesting to know how long the clip needs to be before the 5-10 second dropout kicks in. Assuming you can get a short(ish) clip that drops out after a few secs, it would be good if you could stick it on my ftp server so I can try it here.

- Neil.