Video transcoding transrating

3,136 views

Published on

Video Tanscoding and Transrating methods review and comparison

Published in: Technology, Business
0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
3,136
On SlideShare
0
From Embeds
0
Number of Embeds
23
Actions
Shares
0
Downloads
47
Comments
0
Likes
1
Embeds 0
No embeds

No notes for slide

Video transcoding transrating

  1. 1. Video Transcoding & Transrating Yossi Cohen 1
  2. 2. Overview  Full Transcode  Open Loop transraters Coefficient Drop Transrater Re-quantization transrater  Closed loop transrater FPDT 2
  3. 3. Full Transcoder  Full transcoding does full encoding and decoding of the video. Features include: Easy Implementation Usually used for  format conversion such as MPEG2 Video->H264  Video Resize and frame rate reduction Highest CPU requirements 3
  4. 4. Aided Transcoder  Full decoding of the video  Encoding Video while re-using the decoded video information including: Qp selection Motion vectors Block size (8x8, 4x8 etc.) selection MV, Qp 4
  5. 5. Aided Transcoder Features  High CPU requirements  Like Full transcoder, enables:  Resizing  Change of Frame type (P->I, I->P) for sync point changing  Smooth frame rate conversion  Accurate (no drift) transcoding 5
  6. 6. Open Loop Transcoders  Open loop transcoders are fast and simple transrater.  Open-loop – does not correct the drift error created by the transrating on next frames  Introduces drift error into the video – video quality seriously degrades as a function of the distance from last I frame. 6
  7. 7. Coefficient Drop Transrater  Performs only Entropy Decoding/Encoding  Drops some of the coefficients according to psycho-visual models.  Features  Fastest transrater  Poorest video quality per bitrate  Introduce drift 7
  8. 8. Re-Quanitzation transrater  Performs Entropy decoding and dequantization followed by quantization with an Higher Qp (lowers quality & BR)  Features  Fast Transrater  Poor video quality per bitrate  Introduce drift 8
  9. 9. Closed loop transrater (FPDT)  Performs Entropy decoding and dequantization followed by quantization with an Higher Qp (lowers quality & BR)  Adds quantization error from previous frame to next frame to avoid drift Error Store 9
  10. 10. Closed Loop Transrater - Features  Faster then Transcoders  No drift  Quality is transcoder grade per same bitrate 10
  11. 11. Quality / CPU comparison  Line – Quality, Bar – CPU Cycles Coefficient Drop Re-Quantization transrater FPDT Aided Transcoder Full Transcode 11
  12. 12. Frame dropping overview  Frame dropping could improve KPI (5-10%) and reduce CPU load.  Smooth frame drop – convert to any fps, fixed deltaT between frames, frame interpolation. Very high CPU requirements  Regular frame drop – drop any frame introduce some jerkiness  Limited fps – cant drop any frame, introduce higher jerkiness 12
  13. 13. Frame Dropping -2  Transcoders support both Regular frame drop  Transraters only supports limited fps frame drop  FPDT transrater might support regular frame drop at additional development time 13
  14. 14. Frame Resize  Frame Resize could considerably lower bitrate.  CPU - Requires per pixel operations for resizing – higher CPU but lower encoded frame size which lowers CPU.  Transcoder could easily support resize – additional CPU requirements  FPDT could support resize but would cost considerable CPU and development time 14
  15. 15. Thank you! More About me:  Video Expert  Lectures on Video / Android / VoIP  Android Native Developer Yossi Cohen yossicohen19@gmail.com http://www.mobilevideotech.com +972-545-313092 15

×