search for: macroblock

Hi, So I have almost completed a new VP3 decoder implementation. In the course of doing so, I have encountered something odd about macroblock 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...

...ty 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 stored in the same order? Except for that how should the program decide what kind of coding mode to use? Thank you in advance Nick

...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....

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 MSCHEM...

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

...ribe 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 output. 2. Corresponding 6 blocks from the previous frame are fetched from the same FB in parallel, subtracted from the new frame (if it is not a golden) and processed by the DCT and quantizator. 3. After the quantizator data in one branch goes through dequantizator, IDCT and back to FB to...

...own - the optimization are the same for progresive video - if video multiple of 2 and 1/2 of resolution is not multiple of 16 aspect ratio avoied putin the black bar in the center of the frane betwen the odd and de iner part for up to optain multiple of 16 resolution for less field-macroblock interference. - if the decoder is not capable to posproces de interlazed video, if we use the estandar cut system to indicate the upper field coded in the frame the decoder only show this field, the other is the same but start to the botton intested to start from the top the cut area....

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 orig...

...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 mips has delay slots, not because it has detected any true violations. $ llc macroblock.llvm.mips64el.ll -mcpu=mips64r2 -O3 -o macroblock.s -mattr=n64 -verify-machineinstrs # After PreEmit passes # Machine code for function start_macroblock: Post SSA BB#0: derived from LLVM BB %entry Live Ins: %A0_64 %T9_64 %RA_64 %S3_64 %S2_64 %S1_64 %S0_64 BEQ %A0<kill>, %ZERO, <B...

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

...LOCK1 using raster order (i'm right?) > > Now i'm confused - so much types of ordering. What i must do after DCT? > > What is order for pass blocks to Huffman block? > > In Theora terminology, a 16x16 unit spanning all 3 color planes (8x8 in U > and V) is called a "macroblock". To encode the contents of a macroblock, > you must separate out the different color planes, and form "superblocks" > in each color plane. The DC coefficients of each block are then coded in > "raster order", while the AC coefficients are coded in "coded or...

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

...trates, though this is not a MPEG-4 codec. It appears this proprietary format scales better at low bitrates, while MPEG-4 rapidly taking over for image quality once bandwidth reaches 1000+ Kbps ranges. Due to the nature of its format VP3 tends to blur images as data rates fall instead of creating macroblock artifacts like MPEG-4. *** <p><p>--- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage: http://www.xiph.org/ogg/ To unsubscribe from this list, send a message to 'theora-request@xiph.org' containing only the word 'unsubscribe' in the body. N...

...ating 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 (buffer was written in macroblock-scan order) and applies Huffman encoding (currently there is room for 30 tables of 80) so just a single block RAM is used. Maximal code length is limited to 14 bits, but standard tables have not more than 13 so it is not a problem. This module also combines single EOB tokens if possible. Resul...

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