[vdr] clarification request: vdr file format?

Pasi Kärkkäinen pasik at iki.fi
Thu Aug 25 15:15:22 CEST 2005


On Wed, Aug 24, 2005 at 06:41:25PM +0200, Udo Richter wrote:
> jik jikman wrote:
> > Some sites say it is pva format, some other say it is pes format and
> > other say it is ts format without pat/pmt tables.
> > 
> > What is vdr file format at last? and why we can't record directly in
> > mpg ( mpeg ps ) format as we can do in windows?
> 
> Some clarifications about terms AFAIK:
> 
> Elementary Stream (ES):
> Video stream, audio stream or similar data stream.
> 
> Packetized Elementary Stream (PES):
> ES cut into a sequence of packets. Since all PES packets of one ES share
> one stream id, its possible to mix PES packets of several ES streams
> into one PES stream. PES also adds information for time synchronization
> of the streams.
> 
> Transport Stream (TS):
> Mainly used for live streams. Another packet stream that packs several
> PES streams, each containing only one ES stream, into small packets for
> transport. The streams are separated by the packet identifier (PID). TS
> also adds data packets describing the contents of the stream.
> 
> Program Stream (PS):
> The classic mpeg2 video file format. PS packs several PES packets of
> different ES streams into 'packs'. Also, PS has info headers describing
> the contents of the PS.
> 
> 
> PES is not meant to be a file format, its just an internal stream
> format. PES or similar formats are widely used by PVRs because data of
> TS streams can easily be extracted into PES streams. However, PES as
> file format has several disadvantages:
> 
> - No content information headers, streams may appear or disappear at any
> time. No way to tell exactly whats in it without scanning the whole file.
> 
> - Strange A/V syncing, like audio starting a second earlier than video,
> or audio and video not having the same length.
> 
> - Discontinuities. There may be gaps of several minutes in video and
> audio data (cut out). No way to tell how long a video is without
> scanning the whole file.
> 
> 
> Converting from PES to a well-formatted PS is a tough job, thats why
> there are special programs doing that job. Directly recording into PS
> wont make it easier.
> 

So converting from TS directly to PS would be the best choise.. ? 
TS still contains the timing information..

vdr has access to TS stream, so it could save in TS format, or convert to 
correct/synced PS format?

-- Pasi

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