[vlc-devel] Re: PTS is out of range (), dropping buffer, late picture skipped

[Jean-Paul Saman]

Bart Kerver wrote:
> Hope this helps...
> 
> [bart at video vlc-0.6.1-test1-patch-BART]# ./vlc udp:@233.81.233.12:12345 
> --mtu=16384 -vvvv &> ./log.txt
> 
> [bart at video vlc-0.6.1-test1-patch-BART]# more log.txt | grep mtu
> [00000310] access_udp input debug: using mtu (16384)
> [00000310] ts_dvbpsi input debug: using mtu (16384)
> [00000310] ts input debug: using mtu (16384)
> 
> 
> [00000310] mpeg_system input warning: packet corrupted, PES sizes do not 
> match
> [00000310] mpeg_system input warning: garbage (0xad614481)
> [00000310] mpeg_system input warning: garbage (0xe3a267cc)
> [00000310] mpeg_system input warning: garbage (0x3e01fc4d)
> [00000310] mpeg_system input warning: packet corrupted, PES sizes do not 
> match
> 
> hmmm...
> 
Look at your settings inside /proc/sys/net/core. My values are:

cat /proc/sys/net/core/rmem_max
65535
cat /proc/sys/net/core/rmem_default
65535
cat /proc/sys/net/core/optmem_max
1024
cat /proc/sys/net/core/netdev_max_backlog
300

So if I start calculating with my values, then with an mtu of 16384 I 
can keep 3 packets inside my socket buffer. This is way to little to 
survice some scheduling latency and will definitly result in corrupted 
packets, because when more packets come in packets in the buffer are 
dropped without notice (default behaviour of udp). I would try enlarging 
these buffers to a value that can hold approximately 30 or 40 of those 
big packets..

E.g:
/sbin/sysctl -w net.core.rmem_max=655360
/sbin/sysctl -w net.core.rmem_default=655360
/sbin/sysctl -w net.core.netdev_max_backlog=3000

Maybe this will help to get a better reception of those packets.

This is the explanation for these values in proc/sys/net
- core.optmem_max=10000000, maximum amount of option memory buffers, 
default 10240
- core.rmem_default=10000000, default receive socket buffer size, 
default 65535
- core.rmem_max=10000000, maximum receive socket buffer size, default 131071
- core.wmem_default=10000000, default send socket buffer size, default 65535
- core.wmem_max=10000000, maximum send socket buffer size, default 131071
- core.hot_list_length=300000, maximm number of skb-heads to be cached, 
default 128
- core.netdev_max_backlog=300000, number of unprocessed input packets 
before kernel starts dropping them, default 300

-- 
Kind greetings,

Jean-Paul Saman



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