LAV Filters - DirectShow Media Splitter and Decoders

[Vasilich]

DoctorJ, look there http://www.codecguide.com/windows7_p...er_tweaker.htm

[DoctorJ]

Originally Posted by Vasilich

DoctorJ, look there http://www.codecguide.com/windows7_p...er_tweaker.htm

Yep, know about filter tweaker but I was hoping for something more end user and less tweaking. Does not make sense to make a decoder install package that does not default to being used after install.

[nevcairiel]

Mostly because many actual players disregard the "preferred" codec thing Microsoft came up with, plus overriding this option can break a bunch of things (mostly TV related in WMC/WMP), so as a consequence for many players not actually needing it, and it possible breaking things.. it works just fine like this.

Additionally, those entries are actually thoroughly protected by the OS, and modifying them is a tad bit annoying.

[DoctorJ]

Originally Posted by nevcairiel

Mostly because many actual players disregard the "preferred" codec thing Microsoft came up with, plus overriding this option can break a bunch of things (mostly TV related in WMC/WMP), so as a consequence for many players not actually needing it, and it possible breaking things.. it works just fine like this.

Additionally, those entries are actually thoroughly protected by the OS, and modifying them is a tad bit annoying.

My player uses the preferred so using filter tweaker is the only way to get LAV to work. If it can be done by filter tweaker then can it be done on install? Need something an end user can install and be done with.

[clsid]

Changing the preferred DirectShow decoders is pretty safe. The options that can break stuff are mostly the ones that disable the MS codecs. Live TV needs the MS DTV-DVD video decoder.

[mzso]

Originally Posted by nevcairiel

The file does have screwed up timestamps.
On several occasions, the timestamps go backwards for a bit, and then jump back forward to their proper time.

To ensure proper audio/video sync, LAV will try to obey input timestamps as good as possible, which results in audible glitches in this sample.
If such problems are short enough, LAV can detect and simple ignore them, but if the problem persist for a bit and only corrects itself later, LAV thinks there was a timestamp gap or something like that, and has to adjust accordingly.

So in short, timestamps are wrong.

PS:
Other decoders may ignore small timestamp offsets and not show the glitches because of that, but that might easily result in out-of-sync audio instead, so its not an option really.

Huh. Good to know.
Are these timestamps in the container file (meaning mkvmerge's fault)?
(I would have tried with ffmpeg but the concat filter was not designed for human beings, and I didn't find any usable gui-s.)

[nevcairiel]

Yes, the timestamps are in the container.

[betaking]

can not comp last git

[filler56789]

^ Fixed:

http://code.google.com/p/lavfilters/...f542485d718a9a

[THP]

I was wondering if anyone has been able to correctly decode the Samsung Transformers 4K clip?

I think there is an issue with the LAV splitter/source with that clip. Every +-2 seconds, there seems to be a hickup in the motion, as if there is a frame missing or being skipped. The reason I think it's a problem in the splitter/source filter is that I've tried using different HEVC/h265 decoders in a graph and all of them showed this behavior, of course always using the LAV splitter/source.

What I didn't find was an alternative to LAV splitter/source which works with this specific file so I could say for sure that the problem is indeed with the LAV splitter/source filter.

[nevcairiel]

From what I can tell, there is a bug in the FFmpeg/OpenHEVC HEVC decoder that causes that, any software based on that would suffer from the problem. Its not a source filter issue.
Of course the alternative might be that the HEVC stream is actually not 100% compliant, which causes these hicups.

[THP]

Hmm, interesting, so if I would want to create a valid stream starting from this faulty stream, which tools could I use? I have tried TSDoctor before on this stream, but the HEVC stream wasn't detected properly. I don't know of a any other tools that support HEVC content.

It does seem though that some players (f.e. a HW player, unknown SoC) are capable of handling this type of files. Could be that Samsung purposely introduced an error/fault in it to prevent it from being played correctly on other devices.

[NikosD]

Originally Posted by NikosD

All 5 HEVC files (4K and UHD) from the link below, don't work with HW Intel HEVC decoder and don't fall back to SW decoder properly.

A black screen with audio only using signature system and MPC-HC x64 v1.7.7.128

They work fine in HW with PotPlayer.

http://www.imaging-resource.com/news...ailable-for-do

Same problem still with LAV 0.63.18 in both internal and external LAV.

Is it the Intel's driver ?

[James Freeman]

Audio question,

Should I downmix to Stereo using LAV or let windows (DirectSound) do it?

I generated a test file with all 5.1 channels hitting -0.1 at the same time, DirectSound does a good job downmixing the matrix and playing them all together, the master fader hits -0.1.

I can't play my test file using LAV because its a multichannel WAV.
Is there a way to force LAV and MPC-HC to play WAV files too?

EDIT:
Figured a way.
I exported FLAC instead of WAV.

LAV downmix is exactly to spec.
DirectSound pans rear channels a little closer to the center and not exactly -3db compared to L/R.
DirectSound also mixes the LFE -10db below the L/R channels which lowers the volume of the overall mix.

[nevcairiel]

I prefer LAVs downmixing over DirectSound because it generally results in a louder mix, and since I generally only use it when i'm at a laptop with somewhat weak speakers, a bit of extra volume without needing after-the-fact boosting or something is always welcome.

[James Freeman]

I use the "Normalize Matrix" function to keep the original dynamics, LAV mix is a little louder because I omit the LFE completely whether DirectSound has a good mix but not exactly to spec and its also keeps the LFE in which is not very good for the Stereo mix.

Thanks nev.

[NikosD]

Originally Posted by NikosD

Tried latest LAV x64 0.63.18 after the FFMpeg update and those pesky 10bit HEVC UHD files from Samsung, are still stuttering during playback.

Any info on that ?

Originally Posted by THP

I was wondering if anyone has been able to correctly decode the Samsung Transformers 4K clip?

Originally Posted by nevcairiel

From what I can tell, there is a bug in the FFmpeg/OpenHEVC HEVC decoder that causes that, any software based on that would suffer from the problem. Its not a source filter issue.
Of course the alternative might be that the HEVC stream is actually not 100% compliant, which causes these hicups.

Since that bug was first mentioned here http://forum.doom9.org/showthread.ph...43#post1695243 almost 2 months ago and because we still don't know what's going on, I decided to do a further investigation.

I tried LAV x64 0.59 - 0.60 - 0.61 - 0.62 versions.

I found out that up to 0.61 version, ALL Samsung clips play just fine.

0.62 version broke that, so I think it's something between those two versions 0.61 - 0.62, probably an FFMpeg update introduced a bug in HEVC decoding, in order to be faster.

Since then, all FFMpeg versions, even latest have this bug.

Case solved (from user point of view)

[clsid]

You can find old builds of FFmpeg here:
http://ffmpeg.zeranoe.com/builds/win32/static/

You could use that to further narrow down when the problem was introduced.

You can submit a bug report here:
http://trac.ffmpeg.org/

[NikosD]

Thanks, but I'm not familiar with those procedures.

That's why I wrote case solved - from user point of view - hoping for a developer to investigate it further.

[clsid]

The procedure is very simple.

1) Test playback with FFplay to find last working and first broken version.
command: ffplay samplefile.mp4

2) Generate FFmpeg output log (preferably with the newest build you can find):
command: ffmpeg -i samplefile.mp4 2> output.txt

3) Submit a bug report. Just give a clear description of the problem and copy/paste the entire log. Adding the date and/or git hash of the last working and first broken build will make their life easier. Upload a sample to www.datafilehost.com (that is their preferred host) and include the link.