(Re)Sync to an MPEG-TS stream fails!

I'm using VLC to display a simple UDP video stream of an Hauppauge HD-PVR box. I publish this stream simply by pushing 7 (cached) 188-byte TS packets over UDP. The HD-PVR box delivers a 1080i/50 MPEG-TS stream with H.264 encoded video and a stereo audio channel.

As long as VLC is up an running at the time the device is opened and the stream is started, all went fine. But if I start VLC while the stream is already running, it mostly isn't able to sync to it. The same happens if I write the transport stream to a file. To avoid the 4GB limit of FAT32 formatted USB memory sticks, I split the files somewhere with in the stream. If I try to play these snippets, 10%-20% of the snippets aren't played!

VLC shows the follwoing messages:

ts warning: TS module discarded (lost sync)
ps warning: this does not look like an MPEG PS stream, continuing anyway
ps warning: garbage at input, trying to resync...
ps warning: found sync code
ps warning: garbage at input, trying to resync...
ps warning: found sync code
....

Once VLC starts parsing PS instead of TS, it doesn't switch back to TS even if I force an new stream (with new TS headers) by reopening the HD-PVR device.

I've recorded three snippets (each 70MB) of video. The first is the stream after opening the device, and the rest are splitted somewhere within the stream (1 minute chunks). The first two parts are playable, the last not! If you are interested in these file, I can upload the file somewhere.

This is not supposed to work. Please use RTP if you want to stream MPEG-TS over the network.

added Status::invalid label

closed

Thanks for the comment. But...

(1) the feature page of VLC shows UDP/RTP as possible streaming protocols.

(2) the recorded files couldn't be played too.

So IMO it is a bug, because it doesn't depend on the "input media".

As far as I can see, it is a bug in the TS demuxer.

By the way. Several other application and settop boxes can play the recorded files.

removed Status::invalid label

reopened

I've found a way to force opening the stored files with the TS demuxer! Doing this solves the problem. There are some "skipping garbage" messages, but after this, VLC resync to the video and all works as expected.

As I supposed in my previous comment, VLC has problems selecting the correct demuxer. If you need the sample file, just send me an email.

The workarounds are:

Use "file/ts:" for files and "udp/ts:" for stream. I have to test the streaming as soon as I have access to a stream again.

This "workarounds" have one drawback. I can call VLC with this prefixes by hand, but the file type associations must be fixed too.

added Component::Demuxers Severity::normal labels

changed milestone to %Bugs paradize

Patch welcome.

Sorry, I have no patch, but a suggestion. The packets of the h.264 HD Elementary Stream are much bigger than the packets of SD video. All the packets that I've seen are up to 64kB in size.

May be thats a problem. If the TS demuxers tries to sync to a new ES header, it may doesn't tries enough bytes? I don't knew the code so that is just an idea. Is there a criterea for the TS demuxer to give up (and try another one) which depends on a byte limit?

If so, it could be a good idea to make this limit dynamic. That means, it should depend on the size of the previouly detected frame dimensions or it should be big enough for HD.

The problem is still active! Anyone working on this? Is there nobody out there, who is playing HD streams?

I'm still waiting for a patch.

Could you upload a sample showing the issue?

@fenrir here are the sample files. The LOG file is recorded with the windows release of VLC. As you can see, the TS module gives up and tries PS without going back to TS.

I have to upload the samples to Dropbox, because Trac limits uploads to 256kB. You don't need a Dropbox account to download the files. Good luck.

http://dl.dropbox.com/u/45866471/vlc-failure-samples/failure.log (12kB) http://dl.dropbox.com/u/45866471/vlc-failure-samples/v111027_080155__fails.ts (8.4MB) http://dl.dropbox.com/u/45866471/vlc-failure-samples/v111027_080213__fails.ts (12MB) http://dl.dropbox.com/u/45866471/vlc-failure-samples/v111027_080234__ok.ts (8.4MB)

All samples are now in http://streams.videolan.org/issues/4373/

changed milestone to %2.0.0 bugs

Fixed by [575dd0f2]

added Status::fixed label

closed

commit 575dd0f2 Author: Laurent Aimar fenrir@videolan.org Date: Thu Nov 3 23:21:10 2011 +0100

Improved TS file detection.

Closed [#4373](https://code.videolan.org/videolan/vlc/-/issues/4373)
(The samples still doesn't work if ffmpeg-mt is enabled, but that's probably a
ffmpeg/libav bug)

Original author: fenrir@videolan.org