[Live-devel] Full HD Contents. trickplay question (with VLC)

[Peng]

sorry, forget editing the title.



On 06/28/2013 09:07 AM, live-devel-request at ns.live555.com wrote:
>
> Note the file "ChunMyung1.ts".  This file was created by applying 'trick play' to the original file, with a scale factor of 1 - i.e., by running:
>            testMPEG2TransportStreamTrickPlay ChunMyung.ts 0 1 ChunMyung1.ts
> Because our 'trick play' works by using I-frames only, this file effectively consists just of the i-frames from the original file.  If you play this file in VLC, you can see that the I-frames freeze starting at about the 10 second mark, and do not resume until about the 1 minute mark.  Does anyone know why?
>
> For another illustration of this, note the file "ChunMyung1-30.ts".  This file was created by applying 'trick play' to the original file, with a scale factor of 1, but starting at the 30 second mark - i.e., by running:
>            testMPEG2TransportStreamTrickPlay ChunMyung.ts 30 1 ChunMyung1-30.ts
> If you play this file in VLC, you can see that the video is 'empty' until about the 30 second mark (i.e., corresponding to about 1 minute into the original video).  Does anyone know why?

Hi, Ross.

I happened to be familiar with both TS and AVC. TS is a very special
media container, whose playout axis is determined not only by PTS and
the computer's system clock, but also by PCR encoded in the stream and
the stream's bitrate, which determines the stream internal time axis.
Very few TS muxers can operate in a complete standard way, one of them
maybe Elecard.

When VLC plays such improperly encoded files, inconsistency between the
stream's internal axis and the computer's system clock may occur, which
in turn leads to freezing pictures. A very simple way to check this,
press ctrl+m when playing, set verbosity to 2, and save the log. There
should be 'latter picture skipped' or 'too late to be displayed'
warnings and 'more than 5 seconds' errors.

Currently I use mobile connection to access internet. 90M is simply too
large for me. When returning home,  I volunteer to debug it.

-- 
Peng