Re: Using Xvid to decode Mpeg4 Short Header Format

Hi Masters,

i am using the xvid filters on my directshow applications and in my application i am connecting the two xvid filters, the encoder and decoder xvid filters for real time video streaming, but along the way i cannot successfully connect the two filters in whatever method i used be it Connect(), ConnectDirect() or RenderStream but still giving me the negative HRESULT value which is equivalent to FAILED, in my application what i did i used the media type to connect the two filtes via pin connection method but i am stuck on the setting of mediatype which is very important in connecting the two filters, i mean i referring to the AM_MEDIA_TYPE structure but i am just into the majortype and the subtype, my majortype = MEDIATYPE_Video, and my subtype = ????(i dont know for xvid),

please help....

thank you in advance,
reno


----- Original Message ----
From: Wagner Cunha <[email protected]>
To: [email protected]
Sent: Friday, March 14, 2008 6:36:25 AM
Subject: [XviD-devel] Using Xvid to decode Mpeg4 Short Header Format

Hi All,

The Xvid decoder is able to decode the "mpeg4 short header format"? I have a IP camera wich compress video this way, but i can't open it with Xvid decoder as other mpeg4 streams from other video devices.

http://lists.mpegif.org/pipermail/mp4-tech/2005-December/006113.html

"*3.6.3 MPEG-4 short header and long header
*Some network video streaming systems specify support for "MPEG-4 short 
header," so it's important to understand this term. In fact it's nothing 
more than an H.263 video stream encapsulated with MPEG-4 video stream 
headers.

MPEG-4 short header does not take advantage of any of the additional 
tools specified in the MPEG-4 standard. MPEG-4 short header is only 
specified to allow backwards compatibility with the H.263 recommendation 
for video conferencing over ISDN and LAN. For practical purposes, MPEG-4 
short header is identical to H.263 encoding/decoding, which gives a 
lower quality level than both MPEG-2 and MPEG-4 at a given bit-rate. The 
image and video quality in "short header" is not close to that of true 
MPEG-4, since it does not make use of techniques that allow it to filter 
out picture information that is not visible to the human eye. Nor does 
it use methods like DC and AC prediction, which can significantly
decrease bandwidth demands.

To clarify a network video streaming system specification, support for 
MPEG-4 is sometimes denoted "MPEG-4 long header," which in other words 
is the mode where the MPEG-4 compression tools are being used.
"
from http://www.axis.com/documentation/whitepaper/video/compression_standards.htm

Thanks in advance,

Wagner.
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