search for: macroblocks

...coding. As a quick overview, VP3 has a notion of fragments (8x8 pixels) and superblocks (32x32 pixels, 4x4 fragments). These apply to each individual plane (e.g., a 64x64 video will have 4 Y superblocks and 1+1 C superblocks, 64 Y fragments and 16+16 C fragments). VP3 also has a notion of macroblocks which are the same as MPEG. I.e., 1 macroblock encompasses 4 Y fragments and 1+1 C fragments. IOW, 1 macroblock applies to all 3 planes, whereas one fragment or superblock applies to 1 and only 1 plane. The confusion comes in the fact that when VP3 initializes, it allocates enough space fo...

Hello there, I'm a university student and our professor assigned us as a project to build a theora encoder/decoder. I need some help on some info that I didn't manage to find in Theora's reference. I am building a function that calculates motion estimation. When making motion estimations must I scan each and every macroblock in coded order? After that the motion vectors should be

...at, even at the lowest quality (ie. "-v 0"), the detail, and overally quality is clearly better than anything else available. On the negative side, at qualities comparable to MPEG4, I've notcied a great deal of blockiness. It's not as bad as blockiness from other codecs, as the macroblocks are much smaller, and the detail of the picture (ie. within the macroblocks) is still quite good, but it's a very bad thing, and detrimental to the video just the same. I am a bit concerned because I did not experience the same issue with the handful of standard VP3 videos I've tried. A...

Hi I'm trying to make sense of the macroblock coding modes in section 7.4 of the Theora spec. The text in the specification is: (d) For each consecutive macro block in coded order (cf. Section 2.4) indexed by mbi: i. If a block bi in the luma plane of macro block mbi exists such that BCODED[bi ] is 1: A. If MSCHEME is not 7, read one bit at a time until one of

Hi, I have been on a documentation kick recently. I finally updated my VP3 format document tonight: http://www.pcisys.net/~melanson/codecs/vp3-format.txt v0.2: October 9, 2003 - expanded section "Reversing the DC Prediction" - added Appendix B: Theora Differences Feel free to look it over and point out any glaring mistakes. I can't wait to see how much sense it makes to

Hi Akira, > I am running into a problem when I turn on post-RA scheduler with mode > "ANTIDEP_CRITICAL" for mips. > I'd appreciate if someone could explain what is going wrong here. All these passes are pretty sensitive to correct register liveness information. As a first step I'd check whether machine verifier reports no errors here. -- With best regards, Anton

Here http://lists.xiph.org/pipermail/theora/2004-September/000619.html Andrey describe encoder structure, this like: "I see the following structure of the compressor implemented in the FPGA (Xilinx Spartan 3 1000K gates): 1. Data from the external frame buffer (FB) memory goes to the Bayer-to-YCbCr (4:2:0) converter in overlapping 20x20 tiles that produce 6 8x8 blocks (one macroblock) on the

I don´t found any patent around this but i ned help with the patents. I can´t found all patents for interlazed video and I only read the patents around MPEG , the optimization for field based video can be aplied without problem, this is compatible whih the progresive encoding and in a few scenarios they can be positive. <p>process: <p>common: -2 bits to indicate video type 0x

I hope this list is small enough for not beeing banned when introducing oneself. So... Hi, I just subscribed to the theora-lists. I'm from the XVID project, so I know a deal about video and MPEG-4 in particular, but nothing about Vorbis/Theora etc., That's why I'm here, because I'm interested in patent-free alternatives. I guess there is no documentation of the current status

...reading the Theora spec (which I will freely admit I have not read before; I only read the specs on VP3 back when it was first released), I expect that all patents on the following topics apply: Forward motion compensation Half-pel motion compensation Motion vector precision/range Skipped P-frame macroblocks Macroblock prediction IP frame followed by another P field (wtf?) Possibly anything else relation to motion estimation or quantization. In addition, I expect there are patents covering the loop filter used in Theora; however these don't overlap with mpeg1/2 so they weren't part of my origi...

Hi Anton, Thanks for the suggestions. I compiled the .ll file with llc with command line options -verify-dom-info, -verify-regalloc and -verify-loop-info. I didn't see any diagnostic messages. When I add -verify-machineinstrs, it complains that there are instructions after terminator instructions. It seems that these error messages are printed because the verifier does not understand that

Hi, Is somewhere alghorithm description of encoder process implemented in libtheora? May be some drafts? May be frame dataflow throw encoder stages? PLEASE -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.xiph.org/pipermail/theora/attachments/20110318/c3e8e109/attachment.htm

I am running into a problem when I turn on post-RA scheduler with mode "ANTIDEP_CRITICAL" for mips. I'd appreciate if someone could explain what is going wrong here. This is the basic block before post RA scheduling (at PostRASchedulerList.cpp:322): *(gdb) #3 0x0000000000ed3d26 in runOnMachineFunction (this=0x20aa470, Fn=...) at lib/CodeGen/PostRASchedulerList.cpp:322 322

---------- Forwarded message ---------- From: digital design <developer.fpga at gmail.com> Date: 21 March 2011 13:38 Subject: Re: [theora] alghorithm of working encoder in libtheora To: bens at alum.mit.edu Cc: Reply-All at xiph.org On 18 March 2011 23:15, Benjamin M. Schwartz <bmschwar at fas.harvard.edu>wrote: > On 03/18/2011 01:44 PM, digital design wrote: > > Now i

Dan, In reviewing the code, derf came across the DCSearchPoints array in QuadCodeDisplayFragments(), encode.c:696. It looks like it specifies a search order for nearby coded fragments for prediction if there isn't a nearest neighbor. However, the upper search bound is defined as *0*, so the search loop (line 917) is never executed and it always falls back to the last coded fragment.

https://bugs.freedesktop.org/show_bug.cgi?id=89572 Bug ID: 89572 Summary: [NV86] Video playback corruption with nouveau, vdpau Product: xorg Version: unspecified Hardware: x86-64 (AMD64) OS: Linux (All) Status: NEW Severity: normal Priority: medium Component: Driver/nouveau

The site: http://www.techimo.com/articles/index.pl?photo=33&SID=12&tag=SNnb323 has a review & comparison of several mpeg-4 codecs, and they also include vp3. (Be warned, it's a very big web page, due to all of the image examples!) Not really all that informative, but I thought somebody might be interested in hearing about it. *** On2 VP3 3.2.5.0 Positive: extreme low bitrate

Andrey posted the following update at his sourceforge web site. I'm sharing it here because I think it is fascinating to see the progress in his FPGA implemention of the Theora codec as it happens. John <snip> Wrote code and partially simulated compressor_two module with submodules. It gets fixed-width (12-bits) "pre-tokens" from the frame buffer in the coded order

Theora can encode video with several quality parameters. So when that encoded video is decoding it should be looked at quality value. For a single video, decoder get first frame quality value for all video frame or decoder get each quality value for each frame? -- Asanka Dilruk Department of Computer Science and Eng. University of Moratuwa.... http://www.asankadilruk.blogspot.com/ --------------

Hi, I am using theora codec to stream video. Sometimes I am getting (due network actions- packet loss / delay) a distortion in the video image degrading its quality and I think it is something related to the video slices / chunks (dropped or disordered) of the entire frame. Are there plans for slicing and loss detection/resilience built-in theora codec? Will theora codec have a similar approach