FF/REW bad colors

[leoenc]

When fast forwarding or rewinding an x264 encoded stream (wrapped in TS) via a certain set-top box, I'm getting red-blue colors, like the decoder cannot decode all the colors properly.

Obviously there's nothing wrong with the x264 encode itself, as it plays back perfectly. The weird colors are just shown in trick-play modes. So I figure it must be a limitation of the decoder itself.

I have tried various x264 settings, reverting to a simple superfast preset but cannot solve this issue.

Anyone has a clue?

Thanks

[Guest]

It's just bad trick mode implementation. You have to manage the SPS/PPS injection properly and it's not a trivial thing. You can't just seek to an I frame and expect everything to be hunky-dory. You have to have the proper SPSs and PPSs in effect.

[leoenc]

But how can I control SPS/PPS with x264?
All I see documented is --sps-id.
How can I control where SPS/PPS are inserted in the stream?

[Guest]

Can you post a screenshot of the bad colors? I want to see if I can tell what kind of seeking issue is involved.

Which STB is this?

[leoenc]

Sure, here it is:
http://imageshack.us/photo/my-images/546/image003af.jpg/
Sorry about the miniature size, it was taken with someone's phone. I'm afraid I can only get details about the STB next week.

[Guest]

I've never seen anything like that. Can you provide a stream sample that includes that frame?

[leoenc]

Yes, I can do that after the weekend.
Thanks!

[leoenc]

Here is a sample from a stream that was tested to show this issue:
http://www.mediafire.com/?dztn684mdf6xxet
The STB is a Thomson.

[leoenc]

@neuron2,

Have you a chance to look at the stream?

[Guest]

I don't see anything amiss with the stream and it shows no seeking issues with my software. I suppose we have to conclude that the SW in the set-top box is flaky.

[leoenc]

Thanks neuron2.

I'm reading that the STB manufacturer (Thomson/Technicolor) has filed for bankruptcy recently, so I don't see any software updates coming soon...

[Ghitulescu]

The STB is a Thomson.

Have you tried to search for the forum discussing that particular STB, maybe this issue is known and maybe a solution and/or a workaround have been found?

[shroomM]

STBs can sometimes be a pain in the ..., especially old and obsolete ones.

My suggestions...
First and foremost: you set your keyint to 33 but the VBV buffer size to 15000.
This means the STB will buffer the video for 2 seconds on trick play (vbv_bufsize / bitrate = 15000/7500 = 2).
Set the VBV buffersize to the same value your bitrate is at, that is, 7500.

The next thing you could try is, how does your STB behave with a progressive stream, not an MBAFF one. Also an SD one.
It may not solve your particular problem, but may help you identify the issue further.

It may also be an incompatible TS muxer (or rather, a muxer that the STB doesn't like).

You could and should try OBE-VoD - http://code.google.com/p/open-broadcast-encoder/downloads/list.
It's an x264 based encoder, which includes a TS muxer.
I use it exclusively when generating TS output as I've had zero problems with STBs I'm working with - in contrast, I've had numerous issues with other muxers.

STBs suck.

[leoenc]

Thanks guys but I've already tried everything you suggested and nothing helped.
The annoying thing is that with another (commercial) encoder - it works just fine.