1 / 21

Quantitative Comparison of H.264/AVC and VP8 Video Codecs for Video Conferencing

Quantitative Comparison of H.264/AVC and VP8 Video Codecs for Video Conferencing. Scott Kristjanson CMPT-820 Multimedia Systems Instructor: Dr. Mohamed Hefeeda Dec 2 nd 2010 . Presentation Overview. Project Overview Methods Results Conclusions Future Work References.

zelia
Download Presentation

Quantitative Comparison of H.264/AVC and VP8 Video Codecs for Video Conferencing

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Quantitative Comparison of H.264/AVC and VP8 Video Codecs for Video Conferencing Scott Kristjanson CMPT-820 Multimedia Systems Instructor: Dr. Mohamed Hefeeda Dec 2nd 2010

  2. Presentation Overview • Project Overview • Methods • Results • Conclusions • Future Work • References

  3. Project Overview • Compare Video Codecs for use with Video Conferencing: • VP8 – by Google’s WebM project • H.264/AVC – used x256 Open Source Codec

  4. VP8 Overview • Video Codec owned by Google and made open Source • WebM Project: Matroska container with VP8 video and Vorbis audio • VP8 - Earlier versions VP7 (Skype), VP6 (Flash Video), VP3 (Theora) • Key Features: • Adaptive Loop Filtering – Identifies Fast/Slow/Static regions and adapts encoding to match for improved quality/performance • Golden Frames – for storing reference point to background layer. Can be used for reference without display them. • Faster encoding time by avoiding use of Arithemetic VLE (CABAC). • Dynamically scales resolution. No need to involve application, encoder decides. No I-frame required as a transition point. • Structure: • Frame same as H.264, Segment like a Slice • Partitions used to separate critical data from video data • I-Frame, P-Frames, Golden-Frames, no B-Frames due to Patents For more information, see Google’s “Intro to VP8” slides at: http://www.slideshare.net/DSPIP/google-vp8

  5. Methods • Quantitative Comparison: Invoke encoders/decoders with various presets: • Manually from DOS, then use YUV_Compare to compute Y-PSNR • ViCoS Codec Comparison utility from MSU – gives ranking only • Used sequences foreman and salesman to simulate video conference calls • Encode with bit rates 100, 800, 1500 kbps to produce bit rate curves Extract Quantitative Data • Y-PSNR – Signal to Noise Ratio for Luminosity • Y-SSIM – Structural Simularity Data for Luminosity • Encoding Time • Frame Rate • Bit Rate • Qualitative Comparison • View original YUV file and encoded/decoded files using YUVviewer • Test VP8 in Video Conferencing System to verify Quantitative Data

  6. Reference Video Sequences • Salesman • Ideal choice for simulating video conference • Not used since not available in CIF format • Tried to convert from .avi to CIF format but ran out of time • Foreman • Good choice, but with some background movement • Used in detailed quantitative analysis • Used with Vicos for codec over-all evaluation • Mobile • Slow motion with detailed cartoon-like background • Used with Vicos for codec over-all evaluation • Stefan • Lots of motion and lots of background detail • Used with Vicos for codec over-all evaluation

  7. DOS Command Line Testing • x264 encode/decode: • vp8 encode/decode: Visually compare original video to encoded video with YUV_Viewer

  8. PSNR Computing Y-PSNR with AviSynth • AVS script to read and compare two YUV files: • Encoded/Decoded YUV video from DOS command line testing • Original YUV video • yuv_compare_foreman.avs • foreman_yuv_compare.log loadplugin("C:\megui\tools\avisynth_plugin\rawsource.dll") decodedClip = RawSource("C:\foreman_352x288_decoded_vp8.yuv",352, 288, "I420") originalClip = RawSource("C:\foreman_352x288.yuv", 352, 288, "I420") Compare(decodedClip, originalClip, "YUV", "foreman_yuv_compare.log") Mean Max Max Absolute Mean Pos. Neg. Frame Dev. Dev. Dev. Dev. PSNR (dB) ----------------------------------------------------- 0 0.7591 +0.0252 5 -3 47.6277 1 0.7566 -0.0050 5 -4 47.6655 … … … … … … 299 0.8597 +0.0070 4 -4 46.8949 Total frames processed: 300 Minimum Average Maximum Mean Absolute Deviation: 0.6941 1.2438 3.7930 Mean Deviation: -0.2703 -0.0194 +0.0527 PSNR: 33.2940 44.9776 48.2338 Overall PSNR: 41.3285

  9. MSU’s Video Codecs Scoring System (ViCoS) • Allows custom Codecs to be bound in and tested • bind in encoders and decoders (x264 and vp8) • define encoding and decoding parameters and presets to be tested • encodes/decodes test sequences automatically and computes distortion • generates relative ranking and relative scores for PSNR and SSIM only • Versions: • Demo version used – provides ranking scores only • Professional version – creates PNSR/SSIM charts automatically

  10. Video Quality – Peak Signal to Noise Ratio (Y-PSNR) • Bit-Rate/Quality Trade-Off: • 100kbps – Poor Quality • 800kbps – Acceptible to good • 1500kbps – Very Good to Excellent PSNR Ranges: 38+ Excellent 36-37 Very good 34-35 Good 26-33 Poor 25 or less Garbage

  11. Video Quality – Structural Simularity (SSIM) • SSIM score under 0.95 is quite noticible: • 100kbps – Poor Quality for all codecs (especially x264 Fast Zero-Latency & Ultrafast) • 800kbps – most codecs Acceptible to good (except VP8 RT CBR and x264 Ultrafast) • 1500kbps – all Very Good (except x264 Ultrafast)

  12. Encoder Frame Rates • x264 Encoder significantly faster than VP8 for similar Quality

  13. Codec Preset Good Codec Presets for Video Conferencing • Need min of 15 fps for Video Conferencing, prefer 30 fps • Want decent quality – Y-PSNR of 34 or better • Low Latency: under 150ms required • 4 Presets met these requirements:

  14. Conclusion • VP8 and x264 provide similar video quality • For higher bit rates, x264 PSNR better by 2% • For lower rates, VP8 wins by almost 10% • x264 provides better performance in some cases • x264 is between 36% and up to 2x faster than VP8 • A big improvement! VP8 used to be 5-20 times slower!

  15. References: • [1] Image Quality Assessment: From Error Visibility to Structural Similarity • Zhou Wang, Alan Conrad Bovik, Hamid, Rahim Sheikh, and Eero P. Simoncelli • IEEE Transactions on Image Processing, Vol 13, No. 4, April 2004 • http://ieeexplore.ieee.org.proxy.lib.sfu.ca/stamp/stamp.jsp?tp=&arnumber=1284395 • [2] 6th Annual MPEG-4 AVC H.264 video codecs comparison • D. Vatolin, D. Kulikov, and A. Parshin, April 2010 • http://compression.ru/video/codec_comparison/h264_2010/

  16. Backup Slides

  17. H.264/AVC Presets Used • Codecs tested with various presets and tunings • Looking for good balance of quality and speed for video conferencing • Each tested with 3 target Encoding bit rates: 100, 800, 1500 kbps • x264 Presets: • Placebo • 2-Pass Slower Encoding Speed, higher quality • Fast (tested with 2 tunings) • 2-Pass Faster Encoding Speed, good quality • 2-Pass tuned with zero latency specified • Default • 1-pass with default settings • Baseline • 1-pass fast encoding but poor quality at lower bit rates • Ultrafast • When speed is all that matters!

  18. VP8 Presets Used • Best • 2-Pass encoding • Maximimizes Quality but slower encode times • Good 2-Pass • 2-Pass encoding, less quality but faster encode times • measured with 1, 2, and 4 cpu cores specified • Good 1-Pass • 1-Pass encoding, less quality but faster encode times • Fast VBR • 1-Pass variable bit-rate fast encoding • RealTime CBR • Encoder Frame buffer size 6 • with and without deadline specified

  19. VP8 Support for MultiCore Processors

  20. Encoding Bit Rate vs Target Bit Rate • Both Codecs appear to over-run target slightly • VP8 tracks to target bit-rate slightly better

  21. Video Quality – Structural Simularity (SSIM) • SSIM score under 0.95 is quite noticible: • 100kbps – Poor Quality for all codecs (especially x264 Fast 0-Latency and Ultrafast) • 800kbps – most codecs Acceptible to good (except VP8 RT CBR and x264 Ultrafast) • 1500kbps – all Very Good

More Related