[vdr] Latency using vdr-xine

Reinhard Nissl rnissl at gmx.de
Sun Apr 9 20:59:39 CEST 2006


Hi,

CR wrote:

> I don't want this to seem ungrateful or overly critical, but I find when I
> use vdr-xine (not even network vdr-xine) there is an additional 2-5 second
> latency on-top of normal delays before channel changes show up in the
> window.  With softedevice, there is almost no delay, channel changes occur
> <=1.5 seconds.
> 
> I've disabled all vdr-xine buffering (through OSD), hysteresis, etc, but
> the delay still persists.
> 
> In fact, when I change channels, in the terminal that launched vdr, I can
> see "vv" and other messages 2-4 seconds after the log indicates a channel
> change.
> 
> Any planned fixes or suggestions?

Hhm, I took the time of channel switching / buffering operations. Here 
are my results:

SetPlayMode: 0
SetAudioChannelDevice: 0
SetPlayMode: 1
[vVMSetDigitalAudioDevice: 0
SetAudioChannelDevice: 0
aA+++++ 32.684 ms, 131.690 ms, 1.381 ms, (623.324 ms, 950.066 ms, 
1509.274 ms) +++++
]buffered 8.4 frames (v:14.6, a:8.4) <<<<<

SetPlayMode: 0
SetAudioChannelDevice: 0
SetPlayMode: 1
[vVMSetDigitalAudioDevice: 1
SetAudioChannelDevice: 0
aA+++++ 35.194 ms, 132.252 ms, 22.768 ms, (290.630 ms, 619.020 ms, 
1082.295 ms) +++++
]buffered 8.1 frames (v:14.9, a:8.1) <<<<<

SetPlayMode: 0
SetAudioChannelDevice: 0
SetPlayMode: 1
[vVMSetDigitalAudioDevice: 0
SetAudioChannelDevice: 0
aA+++++ 24.086 ms, 137.504 ms, 16.271 ms, (515.649 ms, 638.174 ms, 
1197.297 ms) +++++
]buffered 8.1 frames (v:13.9, a:8.1) <<<<<

SetPlayMode: 0
SetAudioChannelDevice: 0
SetPlayMode: 1
[vVMSetDigitalAudioDevice: 1
SetAudioChannelDevice: 0
A+++++ 44.290 ms, 151.882 ms, 1.311 ms, (415.097 ms, 636.424 ms, 
1399.426 ms) +++++
]buffered 8.2 frames (v:20.3, a:8.2) <<<<<

SetPlayMode: 0
SetAudioChannelDevice: 0
SetPlayMode: 1
[vVMSetDigitalAudioDevice: 0
SetAudioChannelDevice: 0
aA+++++ 40.079 ms, 131.654 ms, 1.598 ms, (207.163 ms, 420.199 ms, 
1173.028 ms) +++++
]buffered 8.1 frames (v:18.3, a:8.1) <<<<<

SetPlayMode: 0
SetAudioChannelDevice: 0
SetPlayMode: 1
[vVMSetDigitalAudioDevice: 0
SetAudioChannelDevice: 0
A+++++ 48.134 ms, 227.605 ms, 2.211 ms, (207.112 ms, 427.153 ms, 872.160 
ms) +++++
]buffered 8.2 frames (v:14.9, a:8.2) <<<<<

SetPlayMode: 0
SetAudioChannelDevice: 0
SetPlayMode: 1
[vVMSetDigitalAudioDevice: 1
SetAudioChannelDevice: 0
aA+++++ 52.188 ms, 136.508 ms, 21.595 ms, (291.351 ms, 626.790 ms, 
973.556 ms) +++++
]buffered 8.1 frames (v:14.2, a:8.1) <<<<<

SetPlayMode: 0
SetAudioChannelDevice: 0
SetPlayMode: 1
[vVMSetDigitalAudioDevice: 1
SetAudioChannelDevice: 0
aA+++++ 48.062 ms, 132.846 ms, 18.384 ms, (501.385 ms, 719.555 ms, 
1156.550 ms) +++++
]buffered 8.0 frames (v:13.3, a:8.0) <<<<<

SetPlayMode: 0
SetAudioChannelDevice: 0
SetPlayMode: 1
[vVMSetDigitalAudioDevice: 0
SetAudioChannelDevice: 0
aA+++++ 32.117 ms, 139.662 ms, 1.396 ms, (207.947 ms, 331.013 ms, 
773.872 ms) +++++
]buffered 8.5 frames (v:15.3, a:8.5) <<<<<

The output shows 5 durations which have the following meanings:

ttt1-ttt0: time to execute cXineDevice::SetPlayMode(0)
ttt2-ttt1: time VDR spends between SetPlayMode(0) and SetPlayMode(1)
ttt3-ttt2: time to execute cXineDevice::SetPlayMode(1)
ttt4-ttt3: time after SetPlayMode(1) up to the first video packet
ttt5-ttt3: time after SetPlayMode(1) up to the first audio packet
ttt6-ttt3: time after SetPlayMode(1) up to establishing the buffer

I've used the following buffer settings: 4, 4, 0.
To debug this issue, please try the attached xineDevice.c which outputs 
the above mentioned numbers.

Bye.
-- 
Dipl.-Inform. (FH) Reinhard Nissl
mailto:rnissl at gmx.de
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