[vlc] [HOWARD JOHNSON <hwjohnso at adtran.com>] Dropping audio on high def clips

Thu May 12 12:41:59 CEST 2005

----- Forwarded message from HOWARD JOHNSON <hwjohnso at adtran.com> -----

From: HOWARD JOHNSON <hwjohnso at adtran.com>
Date: Wed, 11 May 2005 15:35:26 -0500
To: vlc at videolan.org
Subject: Dropping audio on high def clips
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I am having consistent, reproducible problems using VLC as server and 
client with streaming/playing a looped MPEG-2 high definition video clip

with A/52 audio encoding.  In a nutshelI, when looping this type of 
video, every other iteration of the video looses sound for the entire 
length of the clip.  So the 1st, 3rd, 5th, 7th etc... iterations play 
fine for both audio and video but the 2nd, 4th, 6th etc... iterations 
play only the video.  It seems as though the problem is with the 
client.  If you stop the VLC client on an even number iteration and 
restart the client then both audio and video play.

The first set of messages captured show the A/52 audio stream detected 
and the audio module a52 is selected.  The second set of messages shows 
what happens with the 1st iteration ends and the 2nd begins.  For some 
reason the audio stream is not detected.  And like I said, on the 3rd 
iteration, the client re-dectects the A/52 audio and loads the a52 
module and then both audio and video play normally.

The server is invoked as follows:
    "vlc Route_66.mpg  --sout-keep --loop --sout udp:224.1.1.1 --ttl 12"

And the client is invoked as follows:
    "vlc -vout x11 --nofullscreen udp://@224.1.1.1"

This anomaly is happening on two different client machines running 
vlc-0.8.1 but running different Linux distributions.

Any ideas would be appreciated.

main debug: looking for decoder module
main debug: probing 19 candidates
main debug: using decoder module "libmpeg2"
a52: A/52 channels:2 samplerate:48000 bitrate:384000
main debug: looking for audio output module
main debug: probing 4 candidates
main debug: thread 229386 (decoder) created at priority 0 
(src/input/decoder.c:157)
ts warning: first packet for pid=76 cc=0xf
ts warning: discontinuity received 0x3 instead of 0xc
alsa debug: opening ALSA device `default'
libmpeg2 debug: 1920x1088, aspect 768000, 29.971 fps
main warning: dts != current_pts (-2808074)
main debug: thread 245766 (aout) created at priority 0 (alsa.c:603)
main debug: using audio output module "alsa"
main debug: output 'fl32' 48000 Hz Stereo frame=1 samples/8 bytes
main debug: mixer 'fl32' 48000 Hz Stereo frame=1 samples/8 bytes
main debug: no need for any filter
main debug: looking for audio mixer module
main debug: probing 3 candidates
main debug: using audio mixer module "trivial_mixer"
main debug: input 'a52 ' 48000 Hz Stereo frame=1536 samples/1536 bytes
main debug: filter(s) 'a52 '->'fl32' 48000 Hz->48000 Hz Stereo->Stereo
main debug: looking for audio filter module
main debug: probing 22 candidates
main debug: using audio filter module "a52tofloat32"
main debug: found a filter for the whole conversion
main debug: filter(s) 'fl32'->'fl32' 52800 Hz->48000 Hz Stereo->Stereo
main debug: looking for audio filter module
main debug: probing 22 candidates
main debug: using audio filter module "bandlimited_resampler"
main debug: found a filter for the whole conversion
main warning: vout synchro warning: pts != current_date (-33355)
main warning: late picture skipped (-10547)
main debug: stream periodicity changed from B[1] to B[2]
a52 debug: emulated sync word (no sync on following frame)
main warning: buffer is 69723 in advance, triggering downsampling
ts warning: discontinuity received 0xb instead of 0x1
ts warning: discontinuity received 0xc instead of 0x8

...snip

ts debug: PMTCallBack called
ts debug: new PMT program number=1 version=6 pid_pcr=78
ts debug:   * es pid=78 type=129 fcc=a52
ts debug:    * descriptor : unknown (0x5)
ts debug:    * descriptor : unknown (0xa)
main debug: unlocking module "a52"
main debug: thread 213001 joined (src/input/decoder.c:189)
main debug: killing decoder fourcc `a52 ', 49 PES in FIFO
main debug: unlocking module "a52tofloat32"
main debug: unlocking module "bandlimited_resampler"
main debug: thread 245766 joined (alsa.c:655)
main debug: unlocking module "alsa"
main debug: unlocking module "trivial_mixer"
main debug: unlocking module "libmpeg2"
main debug: thread 229386 joined (src/input/decoder.c:189)
main debug: killing decoder fourcc `mpgv', 60 PES in FIFO
ts debug: PMTCallBack called
ts debug: new PMT program number=1 version=7 pid_pcr=79
ts debug:   * es pid=78 type=129 fcc=a52
ts debug:    * descriptor : unknown (0x5)
ts debug:    * descriptor : unknown (0xa)
ts debug:   * es pid=79 type=2 fcc=mpgv
main debug: looking for decoder module
main debug: probing 19 candidates
main debug: using decoder module "libmpeg2"
main debug: thread 262150 (decoder) created at priority 0 
(src/input/decoder.c:157)
ts warning: first packet for pid=78 cc=0xf
ts warning: discontinuity received 0x2 instead of 0xb
libmpeg2 debug: 1920x1088, aspect 768000, 29.971 fps
main warning: dts != current_pts (-2807333)
main warning: late picture skipped (74948)
main warning: vout synchro warning: pts != current_date (-33355)
main debug: stream periodicity changed from B[1] to B[2]
main debug: stream periodicity changed from P[5] to P[4]
main debug: decoded 70/105 pictures

-- 
Howard Johnson
Product Qualification Technician
256.963.8000 x8934
256.656.8001 Cell
Howard.Johnson at adtran.com
www.adtran.com <http://www.adtran.com/>
	Corporate Headquarters
9001 Explorer Blvd
Huntsville, AL 35806

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