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Bug #4219

Transcoding multiple channels from one MUX

Added by Poul-Henning Hemberg almost 8 years ago. Updated over 7 years ago.

Status:
Fixed
Priority:
Normal
Category:
Transcoding
Target version:
-
Start date:
2017-02-10
Due date:
% Done:

0%

Estimated time:
Found in version:
4.1-2425~gcf818c0
Affected Versions:

Description

Setup:

2 x PCTV tripleStick 292e USB Tuners (1xDVB-C/-DVB-T-)
1 x HDHomerun Expand (4xDVB-C Tuner)
Clients: Kodi/XMBC
CPU: AMD 8320 8-Core
OS: Linux Mint 18.1 (Tried on Ubuntu 16.04 LTS, Ubuntu 14.04 LTS - same problem)

Problem (bug) description:

When transcoding different channels from same PID (same tuner as TVH choose the same tuner when from same PID) the picture starts to get unstable. It flickers, start, stops as if transcoder struggles to keep up. But when transcoding from different tuners/pid or even same tuner/pid/channel everything runs smooth. When using "pass" profile there is no problem at all (So I don't believe it's a bandwidth issue nor a CPU issue as the transcoding goes smooth at long as it's from different tuner). The "problem" only occurs when transcoding from same PID/same tuner, different channel.

Suggested fix:

The easy fix would be, to have the opportunity to assign either "one tuner pr. user/client". Or have TVH choose another tuner when same PID/different channel is required by clients.

Very annoying workaround (for others with similar problem):

Make one network (with different nametag) for each user. And then assign each different network to users. Don't forget to make network private AND do not merge channels when mapping them. Also make sure you assign network tag when mapping channels. This would allow you the separate the networks later when you assign them later in users entry.


Files

debug.txt (19.2 KB) debug.txt Debug file from 4.1-2415~ge5f5a42 Poul-Henning Hemberg, 2017-02-10 06:40

History

#1

Updated by Jaroslav Kysela almost 8 years ago

  • Subject changed from Transcoding DVB-C from same PID (different channel) to Transcoding multiple channels from one MUX

It looks really like a performance issue:

2017-02-08 13:24:56.664 [WARNING]:mpegts: too much queued table input data (over 2MB), discarding new

For me: I need to check where's the bottleneck (it seems that the global lock is held too much time).

#2

Updated by Poul-Henning Hemberg almost 8 years ago

Jaroslav Kysela wrote:

It looks really like a performance issue:

[...]

For me: I need to check where's the bottleneck (it seems that the global lock is held too much time).

I thought of that too. But then it should be a problem all way round right? I mean also when transcoding from different tuners. And there is no problem what so ever. I can transcode from 3/4 different tuners without any problems. It's only when same tuner/same mux/different channels. It doesn't add up with any (HW) bottlenecks (I'm not sure about SW encoders). And there is no difference if using USB or network tuner. But is there a way to assign one tuner pr. user/client (other than assigning different networks)?

Best ragards /Poul-Henning (Denmark)

P.S. Thanks In advance

#3

Updated by Joe User almost 8 years ago

Looks like a buffer issue?? When using separate tuners, each stream would have its own buffer, when all channels are from the same mux, whey would share the same buffer. Is it possible to dynamically increase the buffer according to bandwidth?

#4

Updated by Poul-Henning Hemberg almost 8 years ago

Jaroslav Kysela wrote:

It looks really like a performance issue:

[...]

For me: I need to check where's the bottleneck (it seems that the global lock is held too much time).

If anybody need further data or logs to solve this issue the just leave a note here. I'll be as helpful as possible.

#5

Updated by saen acro almost 8 years ago

Test your environment with disabled EPG.
my stb with i use with TVH have 400mhz cpu and 64mb ram and with "pass" streaming i see

mpegts: too much queued table input data (over 2MB), discarding new

when disable EPG all is ok

(for debugging there must have some module in TVH with show cpu usage and lag)

#6

Updated by Poul-Henning Hemberg almost 8 years ago

saen acro wrote:

Test your environment with disabled EPG.
my stb with i use with TVH have 400mhz cpu and 64mb ram and with "pass" streaming i see
[...]
when disable EPG all is ok

(for debugging there must have some module in TVH with show cpu usage and lag)

As described in problem. I do not have the problem in "pass" mode. It's only when transcoding. AND it's only when different channels are chosen from the same mux/tv-tuner. I'm not sure I see the combination of transcoding and epggrap as same issue.

#7

Updated by Poul-Henning Hemberg over 7 years ago

Poul-Henning Hemberg wrote:

Setup:

2 x PCTV tripleStick 292e USB Tuners (1xDVB-C/-DVB-T-)
1 x HDHomerun Expand (4xDVB-C Tuner)
Clients: Kodi/XMBC
CPU: AMD 8320 8-Core
OS: Linux Mint 18.1 (Tried on Ubuntu 16.04 LTS, Ubuntu 14.04 LTS - same problem)

Problem (bug) description:

When transcoding different channels from same PID (same tuner as TVH choose the same tuner when from same PID) the picture starts to get unstable. It flickers, start, stops as if transcoder struggles to keep up. But when transcoding from different tuners/pid or even same tuner/pid/channel everything runs smooth. When using "pass" profile there is no problem at all (So I don't believe it's a bandwidth issue nor a CPU issue as the transcoding goes smooth at long as it's from different tuner). The "problem" only occurs when transcoding from same PID/same tuner, different channel.

Suggested fix:

The easy fix would be, to have the opportunity to assign either "one tuner pr. user/client". Or have TVH choose another tuner when same PID/different channel is required by clients.

Very annoying workaround (for others with similar problem):

Make one network (with different nametag) for each user. And then assign each different network to users. Don't forget to make network private AND do not merge channels when mapping them. Also make sure you assign network tag when mapping channels. This would allow you the separate the networks later when you assign them later in users entry.

Any news on this subject? I have thought a lot about it. Could this be a RAM issue. I only got 8 GB ram in the pc. It should be enough right?

#8

Updated by Jaroslav Kysela over 7 years ago

  • Status changed from New to Fixed

Fixed in v4.3-235-g0310309 .

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