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Mplayer "a52: CRC check failed!" errors, any progr
PostPosted: Tue Oct 11, 2005 6:01 am Reply with quote
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I've seen that several people have been having problems with this.

I'm having the problem with local OTA Fox broadcasts. After a short while of trying to work, mplayer eventually craps out with repeated...

Code:
a52: CRC check failed!   -0.002 ct: -0.398 245/245 37% 13%  0.9% 0 0 10%
a52: CRC check failed!   -0.001 ct: -0.398 246/246 37% 13%  0.9% 0 0 11%
a52: CRC check failed!    0.005 ct: -0.339 307/307 36% 13%  0.9% 0 0 10%
a52: CRC check failed!    0.032 ct: -0.337 311/311 36% 13%  0.9% 0 0 10%


Errors, eventually giving me the list of potential problems.

If I use the -ao mpegpes option (which supresses audio), the video plays fine. I'm using the dvb drivers and apps (obviously). This seems to be an issue with (AC3) audio decoding on Fox, from what I've read.

As ABC also uses 720p, I doubt that it would have to do with 720p vs 1280i.

Has anyone with the a52: CRC errors had any resolution they'd care to share?
PostPosted: Tue Oct 11, 2005 6:02 am Reply with quote
sonnik
 
Joined: 11 Oct 2005
Posts: 49




I'll take credit for the previous post! Very Happy
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PostPosted: Tue Oct 11, 2005 7:20 am Reply with quote
sonnik
 
Joined: 11 Oct 2005
Posts: 49




Just also wanted to point out that this is using the command:

Code:
cat /dev/dvb/adapter0/dvr0 | mplayer -vo xv -


(Note that I've tried various options to help mplayer along). However, if I dump the transport stream to a file and play back later, there are no problems.
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PostPosted: Tue Oct 11, 2005 10:48 am Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




Run mplayer with "-cache 8192".

I bet that will solve everything. I think the demuxer has a problem of thinking it's read more bytes from the device than it really has.
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PostPosted: Tue Oct 11, 2005 11:01 pm Reply with quote
sonnik
 
Joined: 11 Oct 2005
Posts: 49




Thanks, but already tried that.

While both channels offer 60fps, my ABC gives me a larger stream (top) with 5.1 channels and my FOX gives me a smaller stream with only 2 channel AC3.

I've even tried compiling from mplayer's CVS, which seems to be worse.

Code:
Opening audio decoder: [liba52] AC3 decoding with liba52
Using SSE optimized IMDCT transform
AC3: 5.1 (3f+2r+lfe)  48000 Hz  384.0 kbit/s
Using MMX optimized resampler
AUDIO: 48000 Hz, 2 ch, s16le, 384.0 kbit/25.00% (ratio: 48000->192000)
Selected audio codec: [a52] afm:liba52 (AC3-liba52)


Code:

Opening audio decoder: [liba52] AC3 decoding with liba52
Using SSE optimized IMDCT transform
AC3: 2.0 (stereo)  48000 Hz  384.0 kbit/s
Using MMX optimized resampler
AUDIO: 48000 Hz, 2 ch, s16le, 384.0 kbit/25.00% (ratio: 48000->192000)
Selected audio codec: [a52] afm:liba52 (AC3-liba52)
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PostPosted: Wed Oct 12, 2005 8:49 am Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




FOX stations broadcast 5.1 during 5.1 programs. They'll switch to 2.0 during 2.0 programs and commercials.
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PostPosted: Wed Oct 12, 2005 8:56 am Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




Can you eliminate the pipe?

Code:
mplayer -vo xv /dev/dvb/adapter0/dvr0


It's not the best way to pass a stream to mplayer.
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PostPosted: Wed Oct 12, 2005 10:04 pm Reply with quote
sonnik
 
Joined: 11 Oct 2005
Posts: 49




Actually, I had tried that also using gmplayer (in a roundabout way).

I just tried it again using mplayer - still no dice.

Also tried ...

Code:

mplayer -novideo /dev/dvb/adapter0/dvr0


Also produced the CRC issues.

When I was playing around with mplayer source last night, I had it print to console the crc check value, so according to mplayer, it's actually receiving 'faulty' ac3 data.

I also dumped a transport stream through ProjectX ... got this on the audio

Code:
!> missing syncword @  22974, @ 00:00:00.000
!> found syncword @ 23118
-> src_audio: AC-3, CM, 2/0(2.0), dn -27dB, 48000Hz, 384kbps @ 00:00:00.000
!> 10 frame(s) (320ms) added @ 00:00:39.680
audio frames: wri/pre/skip/ins/add 1250/0/0/0/10 @ 00:00:40.000 done...


I had actually seen a few posts at AVSForum.com (Phoenix HDTV thread) that Fox10 was having issues with it's audio recently. It's not widely reported, and I can't really tell if people are STILL having the issue. HDTV display units may be a little more forgiving on the audio if the local Fox station is broadcasting bad audio packets.

I'm kind of skeptical that the local Fox station is having the issue (note I'm getting what looks to be an error free 85% signal). But who knows...

Like I mentioned earlier, If I playback the transport stream (.ts) file (or convert it) there's no issue. Just frustrating I can't watch this one channel live if I want to.
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PostPosted: Thu Oct 13, 2005 5:32 pm Reply with quote
tony
 
Joined: 15 Jul 2005
Posts: 11




Hi Sonnik,
I had the same problem as you, but with viewing QAM content. Every channel would crap out after a few seconds of play.. Some channels play longer, but eventually, will stop working. I found a workaround using a tool called 'dtvstream' which de-muxes the stream you want to disk. Then use mplayer to play the file. I don't know if you can pipe the output to mplayer, but it's nice to have instant replay if you use the previous method.
Tony.
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PostPosted: Sun Oct 16, 2005 11:06 am Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




sonnik wrote:
Like I mentioned earlier, If I playback the transport stream (.ts) file (or convert it) there's no issue.

If the data is wrong, it's gotta be wrong on disk too unless somehow having it on disk allows mplayer to recover from the bad data easier. Does mplayer say it's getting bad crc values when it reads from disk?
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PostPosted: Mon Oct 17, 2005 2:12 pm Reply with quote
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(From sonnik, posting via search history while front page is defaced)

Scott - mplayer does not report crc errors when playing back the .ts dump

I'm trying to get xine working also

tony, haven't tried dtvstream - just curious - if it demuxes, are there two separate streams that must be played?

Also, does it continually write to a file that may eventually clog a mountpoint?
PostPosted: Wed Oct 19, 2005 11:26 am Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




Anonymous wrote:
Scott - mplayer does not report crc errors when playing back the .ts dump

It certainly does. I play corrupted transport stream files all the time with mplayer and see a52 crc errors.

Quote:
tony, haven't tried dtvstream - just curious - if it demuxes, are there two separate streams that must be played?

dtvstream will generate a new transport stream file that contains only the streams you ask for.

Quote:
Also, does it continually write to a file that may eventually clog a mountpoint?

It's no different than any other Unix program that writes to a file.
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PostPosted: Thu Oct 20, 2005 11:29 pm Reply with quote
sonnik
 
Joined: 11 Oct 2005
Posts: 49




Scott Larson wrote:
Does mplayer say it's getting bad crc values when it reads from disk?


sonnik (as anonymous) wrote:
Scott - mplayer does not report crc errors when playing back the .ts dump


Scott Larson wrote:
It certainly does. I play corrupted transport stream files all the time with mplayer and see a52 crc errors.


I was answering your question, dude. I have no doubt that mplayer is capable of reporting crc errors on a file, I'm simply saying it doesn't do it on my captured .ts files

So, for whatever reason, mplayer isn't reporting this on captured my .ts dumps. I'm not triggering verbose output on either mode (live or captured). They show up and the process eventually dies on live output. On captured output, everything is more or less perfect.

All this applies to only my local Fox station.

Every other station, works perfect in both live and recorded with no CRC fails. The CRC errors are only reported when viewing live Fox (KSAZ) broadcasts.

In fact, I compiled a patched (downloaded and modified source) version of mplayer that will actually dump the CRC checksum during playback. Based on my experiences the CRC checksum produces a decimal zero under normal circumstances. The erroneous live playback produces CRC differences (non zero values).
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PostPosted: Fri Oct 21, 2005 9:45 am Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




Another thing you've probably already checked: are there buffer overrun messages in /var/log/messages? mplayer has to be reading wrong stuff from the device somehow.

Also if your Fox station is not sending 5.1 audio then they're not using the splicer Fox provided their affiliates or they've managed to break it. Heaven knows what kind of messed up configuration they're using.

Can you send the output mplayer prints when it starts (one for the file and another for live)?
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PostPosted: Sat Oct 22, 2005 4:01 am Reply with quote
sonnik
 
Joined: 11 Oct 2005
Posts: 49




Scott Larson wrote:
are there buffer overrun messages in /var/log/messages? mplayer has to be reading wrong stuff from the device somehow.

Also if your Fox station is not sending 5.1 audio then they're not using the splicer Fox provided their affiliates or they've managed to break it. Heaven knows what kind of messed up configuration they're using.


Actually, I haven't checked /var/log/messages - I didn't know mplayer logged anything there - but I'll check.

It wouldn't surprise me if KSAZ is doing something wrong, oddly - it's Fox Owned. The only network owned and operated outlet in Phoenix.

I think I saw a blurb of people at AVSForum.com mention problems with KSAZ (http://www.avsforum.com/avs-vb/showthread.php?t=451563&page=29&pp=30 - pages 28-29 of thread)

But no one has complained since the end of September about audio problems.

I'll post some log files when I get home. Also, I'll see if some key network feeds (World Series) offer true 5.1 this week and see if the problems go away when watching those live. I can't seem to assure myself that I've tried it live on a program that should be 5.1 - but I thought I did that during the playoffs last weekend - can't remember what the output was denoted as (5.1 or 2.0).
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