[Live-devel] live-devel Digest, Vol 93, Issue 9

[Sokratis Barmpounakis]

>
> Message: 4
> Date: Tue, 12 Jul 2011 02:14:16 +0000
> From: BONNEAU Guy <gbonneau at miranda.com>
> To: LIVE555 Streaming Media - development & use
>        <live-devel at ns.live555.com>
> Subject: Re: [Live-devel] TestH264VideoStreamer lags in VLC
> Message-ID:
>        <
> 24665DDC0D7CF047BD6471A56E615EA6318123F1 at CA-OPS-MAILBOX.miranda.com>
> Content-Type: text/plain; charset="us-ascii"
>
> Perhaps a bug in VLC.....
>
> I tried with Elecard Stream Eye application and it does see 4 frames per
> second (progressive) in the H264 header and plays at such rate.
>
> GB
>
> From: live-devel-bounces at ns.live555.com [mailto:
> live-devel-bounces at ns.live555.com] On Behalf Of Ross Finlayson
> Sent: Monday, July 11, 2011 20:30
> To: LIVE555 Streaming Media - development & use
> Subject: Re: [Live-devel] TestH264VideoStreamer lags in VLC
>
> Here is an example file :
> http://www.mediafire.com/?rm6v38vx15nd9dv
> When I play it with VLC in my computer it plays normally. So I guess, as a
> encoder output is fine. But when I use for example TestH264VideoStreamer to
> stream it, what the client (also with VLC) sees is much more slow. It is
> like viewing 1 fps, although this sequence's frame rate is much higher.
>
> Actually, "testH264VideoStreamer" thinks that the frame rate is 4
> frames-per-second, and is streaming at that rate.  However, VLC seems to
> stream at about 6 times that rate - i.e., at about 24 frames-per-second.
>
> So, my question - for H.264 experts - is the following: What is VLC seeing,
> in this file, that makes it see a frame rate of 24 frames-per-second, or so?
>
> Our code ("H264VideoStreamFramer") is seeing
>        num_units_in_tick: 1
>        time_scale: 8
>        fixed_frame_rate_flag: 1
> and from this is inferring a frame rate of 4 frames-per-second.  So how is
> VLC inferring a much higher frame rate??
>
> --
>
> Ross Finlayson
>

Thank you both for your feedback. Actually I am setting FPS=4 in the encoder
parameters, so it should be 4. Did you try to stream using live555 lib and
view it in VLC or did you just open it a disk file? Because as I mentioned,
when I run it just a file from disk, it plays normally, without lags or
strange frame rates. But when I use the testH264VideoStreamer or the
testOnDemandRTSPServer applications, I get this strange behavior. So I
assume, it only has to do with the streaming parameters of the encoding (NAL
parameters?). I am not really a h264 expert, just making some thoughts.
Maybe someone can explain this strange behavior.

Thanks once more,
Sokratis
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