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Wlmy97
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- Homework Statement
- When video data is compressed efficiently, there is a variable data rate generated for each video frame; the encoder will generate E(i) bytes to represent frame i, but we might be using a constant transmission rate that transfers T(i)=T bytes each video frame time. A buffer will be needed to allow these two processes to work together.
Similarly, at the decoder, E(i) bytes will be needed to reconstruct frame i and this many bytes will be read out of a buffer that is filled at a constant T bytes/frame.
In this project, you will use data about bit rates generated for sample video sequences to investigate how much buffering is required in the delivery chain for encoder and decoder, and therefore what unavoidable end-to-end delay is involved (no matter how fast the processors are that are doing the encoding and decoding).
By using “frame trace” data (that is, a record of how many bytes are generated for each frame in a compressed video sequence) and recognising that the frames are both generated at the encoder and consumed at the decoder at fixed time intervals, you can simulate the buffers necessary at either end of a transmission link using Matlab or Excel.
These buffers will allow for variable rates to be generated/consumed, even though a constant rate might be transmitted over the network connection. If the buffers are ever allowed to empty, your decoder will be fed blank data; to make sure this doesn’t happen, your simulation should allow them to partly fill before you read anything. out of them.
How will you decide on the bit rate that you simulate between encoder and decoder? How big do the buffers need to be? What delay is involved? Suitable frame trace data is available on the web (see http://www-tkn.ee.tu- berlin.de/research/trace/trace.html, or you may find an alternative source you prefer).
- Relevant Equations
- Transmission rate = Channel bandwidth
1) What is the relationship between buffer at encoder and buffer at decoder?
2) How much preloading is necessary to ensure no buffer empties over the length of the simulation I.e. what is the minimum no. of bytes that must be in the buffer?
3)How to estimate delay due to buffering?
4) What is the minimum buffer size that could feed a frame at every time instance?
5) How big must the buffer be? Why?
6) How do you determine the transmission rate between the encoder and decoder?
2) How much preloading is necessary to ensure no buffer empties over the length of the simulation I.e. what is the minimum no. of bytes that must be in the buffer?
3)How to estimate delay due to buffering?
4) What is the minimum buffer size that could feed a frame at every time instance?
5) How big must the buffer be? Why?
6) How do you determine the transmission rate between the encoder and decoder?