ZikO
18th June 2012, 20:43
Hi,
I have just read an old thread that explains what is Quantization Matrix but I still cannot follow some technical details. I tried to follow the conversation there but I am afraid I could not understand as I was not that advanced yet. I would have a few questions if you don't mind asking.
1. Is the DCT (Discrete Cosinus Transform) something similar to Fourier Transform with regard to audio where we essentially need coefficients to provide a simulation/approximation of a real wave by summing series of sin/cos functions?
2. I believe Quantization Matrix is a set of 64 thresholds in a 8x8 block with highest frequencies at right-hand side and bottom of such block. XviD allows making and applying custom or standard QM with 8x8 numbers. Why are there Intra and Inter QM to use?
3. Am I right to say that the same QM is applied to the each 8x8 block in a frame and to all frames in a video?
4. Can someone explains what are I-, P-, and B-frame.
Also I did not understand why less detailed videos are shorter than let's say videos with high motion and a lot of fine detais in it. From what I read, the same amount of 8x8 blocks is applied. Therefore, the video length should be the same regardless of high or low motion, high or low details in video. What am I missing here?
I will be grateful for any help.
Regards :)
I have just read an old thread that explains what is Quantization Matrix but I still cannot follow some technical details. I tried to follow the conversation there but I am afraid I could not understand as I was not that advanced yet. I would have a few questions if you don't mind asking.
1. Is the DCT (Discrete Cosinus Transform) something similar to Fourier Transform with regard to audio where we essentially need coefficients to provide a simulation/approximation of a real wave by summing series of sin/cos functions?
2. I believe Quantization Matrix is a set of 64 thresholds in a 8x8 block with highest frequencies at right-hand side and bottom of such block. XviD allows making and applying custom or standard QM with 8x8 numbers. Why are there Intra and Inter QM to use?
3. Am I right to say that the same QM is applied to the each 8x8 block in a frame and to all frames in a video?
4. Can someone explains what are I-, P-, and B-frame.
Also I did not understand why less detailed videos are shorter than let's say videos with high motion and a lot of fine detais in it. From what I read, the same amount of 8x8 blocks is applied. Therefore, the video length should be the same regardless of high or low motion, high or low details in video. What am I missing here?
I will be grateful for any help.
Regards :)