Re: Indeo information

Found more info that should clear the situation.

http://research.compaq.com/wrl/DECarchives/DTJ/DTJK04/


'

*Intel's INDEO Video Compression Algorithm.* Intel's proprietary INDEO 
video compression algorithm is used primarily for video presentations on 
personal computer (PC) desktops. It employs color subsampling, pixel 
differencing, run-length encoding, vector quantization, and variable 
word-length encoding. The chrominance components are heavily subsampled. 
For every block of 4-by-4 luminance samples, there is a single sample of 
Cb and Cr. Furthermore, samples are shifted one bit to convert them to 
7-bit values. The resulting precompression format is called YVU9, 
because on average there are 9 bits per pixel. This subsampling alone 
yields a reduction of 9/24. Run-length encoding is employed to encode 
any run of zero pixel differences.

*PCWG's INDEO-C Video Compression Algorithm.* INDEO-C is the video 
compression component of a teleconferencing system derived from the 
Personal Conferencing Specification developed by the Personal 
Conferencing Work Group (PCWG), an industry group led by Intel 
Corporation. Like the MPEG standard, the PCWG specification defines the 
compressed bit stream and the decoder but not the encoder. INDEO-C is 
optimized for low-bit-rate, ISDN-based connections and, unlike its 
desktop compression cousin, is transform-based. It is an interframe 
algorithm that uses motion estimation and a 4:1 chrominance subsampling 
in both directions. Spatial and temporal loop filters are used to remove 
high-frequency artifacts. The transform used for converting spatial data 
to frequency coefficients is the slant transform, which has the 
advantage of requiring only shifts and adds with no multiplies. Like the 
DCT, the fast slant transform (FST) is applied on image subblocks for 
coding both intraframes and difference frames. As was the case in other 
codecs, run-length coding and Huffman coding are employed in the final 
step. Compression and decompression of video in software is faster than 
other interframe schemes like MPEG-1 and H.261.
'

/Benjamin


Mike Melanson wrote:

>On Sun, 21 Dec 2003, Benjamin Larsson wrote:
>
>  
>
>>Found this page on the internet by accident:
>>
>>http://www2.ncsu.edu/eos/service/ece/project/succeed_info/larettin/thesis/ch2.html
>>
>>Intresting parts follow
>>
>>'Indeo is a video compression technique designed by Intel. It evolved
>>from DVI (Digital Video Interactive) technology. Indeo starts off with
>>YUV input, U and V subsampled 4:1 both horizontally and vertically.
>>Indeo supports motion estimation, using the previous frame to predict
>>values for the current frame and only transmitting data if the
>>difference is significant. Transform encoding is done using a 8x8 Fast
>>Slant Transform (FST) in which all operations are either shifts or adds
>>(no multiplies). Quantization and run-length/entropy encoding are used
>>as in previous algorithms. Indeo specifies that the encoded bit stream
>>be a maximum of 60% of the input data, therefore compression is
>>guaranteed to be at worst 1.7:1.'
>>
>>and this paper was written in 1995, so the indeo codec he talks about
>>could be 3.1/3.2 or even 2.1.
>>    
>>
>
>	Try to reconcile this with ffmpeg's Indeo 3 source. I doubt that
>you will find anything resembling a slant transform. Indeo 3 (and 2, I
>believe) are supposed to be vector quantizers. I am pretty sure that the
>slant transform actually applies to Indeo 5, possible Indeo 4 as well.  I
>know that version 4 and 5 were available as of 1997. The earliest software
>I have that uses version 4 has a copyright date of 1996. That paper could
>have also been written based on an Intel press release discussing upcoming
>technology.
>
>--
>	-Mike Melanson
>  
>




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