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VLC player is not properly recording streamed MPEG files
Posted: 30 Sep 2005 14:55
by Rahul_Shukla
I am streaming an MPEG file using VLC and recording it at the receiving end using another VLC using similar HTTP protocol and similar parameters at both end.
I have streamed file 3 times and each time the size of recorded file is different. Am I incurring some n/w losses on HTTP connection? What is the reason behind this mis behavior.
Whether Encapsulation format and chosen protocol UDP/HTTP can affect the receiving VLC's behavior for recording a file.
Any help is welcome..
Rahul
PS: This behavior holds true for both windows and Linux..
Posted: 01 Oct 2005 15:11
by The DJ
VLC remuxes the file when saving it, so in theory it could be different each time.
Posted: 03 Oct 2005 05:01
by Rahul_Shukla
Hi,
Could you please explain the role of encapsulation format used at Transmit and receive side.
I guess first input video file is formatted according to encapsulation format such as MPEG-TS and then it is adapted for given protocol such as UDP, HTTP. At the receive side, first it remove Protocol's header information and create encapsulated stream such as MPEG-TS and then what operations VLC will perform further?
I am still not clear about this remuxing business. Could you please describe a bit more.
Thanks for your help
Posted: 03 Oct 2005 16:45
by The DJ
VLC then receives the stream, removes the protocol information, then reads the MPEG-TS streamformat and creates Elementary Streams (video/audio only) out of it. When you again save this, VLC wraps these ES into a new MPEG-TS stream.
So you get MPEG-PS -> ES -> ES in MPEG-TS -> MPEG-TS in UDP/HTTP on the sending side,
and MPEG-TS in UDP/HTTP -> MPEG-TS -> ES -> ES in new fileformat on the receiving side.
Add packet loss to that on the network, and you see how the files will never be the same.
Posted: 04 Oct 2005 10:44
by Rahul_Shukla
That means, during capturing/remuxing it loses out ES corresponding to non audio-video channels such as Teletext etc. Then it will also loose out numerous stream related information contained in MPEG-4. What happens to BiFS stream of MPEg-4 and suppose if I have put some other type of data in MPEG-4 file.
Thanks
Rahul
PS: Could you suggest other streaming server/client applications which can capture everything on transmission. Will "mpeg4ip" will be of any help.