Contents

1 Intro

Genealogy

 

• Descendant of H.263 (ITU-T Video Coding Experts Group) and MPEG-4 Visual (ISO/IEC Moving Picture Experts Group).¹ In fact, H.264/AVC is the part 10 of the MPEG-4 standard and substitutes the part 2 (visual).

Creation date

 

• End of 2004.

Applications

 

• Used in Blu-ray Discs, DVB-T, DVB-H (Hand-held), video-conferencing (Skype), satellite TV, Internet streaming (YouTube), etc.

2 Differencies with the previous codecs

• Macroblocks of size 16, 8 and 4, in any combination.
• Improved entropy coding: CAVLC (Context Adaptive Variable Length Coding) (Golomb Coding) and CABAC (Context-Based Adaptive Arithmetic Coding) (Arithmetic Coding).
• Up to 16 reference images for the same B macroblock.
• Post compression deblocking filtering which improves the compression ratios.
• Lossless if no quantization is performed.

3 Profiles

• The committee proposes the following set of profiles/levels:
  1. Constrained Baseline Profile (CBP):
     Used in low-capacity devices (such as mobiles).
  2. Baseline Profile (BP):
     Similar to CBP, but with improved error resilience (video-conference).
  3. Main Profile (MP):
     Better compression than BP (TDT).
  4. Extended Profile (XP):
     Better compression than MP and error resilience (Internet streaming).
  5. High Profile (HiP):
     Better compression than XP (TDT HDTV and Blu-Ray).
  6. High 10 Profile (Hi10P):
     The same than HiP, but up to 10 bpp.
  7. High 4:2:2 Profile (Hi422P):
     Equal to Hi10P, but using sub-sampling 4:2:2 (previous profiles only support 4:2:0).
  8. High 4:4:4 Predictive Profile (Hi444PP):
     The same than Hi422P, but using 4:4:4 and up to 14 bpp.
  9. High 10 Intra Profile:
     Equal to Hi10P, but only I-pictures are allowed. Used in video editing.
  10. High 4:2:2 Intra Profile:
      Idem.
  11. High 4:4:4 Intra Profile:
      Idem.
  12. CAVLC 4:4:4 Intra Profile:
      Equal to High 4:4:4 Intra Profile, but with CAVLC instead of CABAC.
  13. Scalable Baseline Profile:
      Scalable extension of the BP profile. Only available in H.264/SVC (Scalable Video Coding).
  14. Scalable High Profile:
      Scalable extension of the HiP profile. Only available in H.264/SVC.
  15. Scalable High Intra Profile:
      Scalable extension of the Intra profiles. Only available in H.264/SVC.
  16. Stereo High Profile:
      3D extension of the HiP profile. Only available in H.264/MVC (Multiview Video Coding).
  17. Multiview High Profile:
      MVC extension of the HiP profile.

Lab

• Compute a R/D curve para H.264 using the x264 command line tool.