Mpeg1

What does MPEG stand for?

Moving Picture Experts Group.

What is the size of the blocks used in the MPEG compression algorithm?

8 × 8.

Which transformation is applied to the blocks in MPEG compression?

Discrete Cosine Transform (DCT).

What term describes the organization of blocks in MPEG?

Macroblocks.

What is the primary function of I frames in MPEG-1?

I frames allow for random access within the video sequence.

What is a significant difference between MPEG-1 and H.261 regarding frame access?

MPEG-1 provides random access capability while H.261 requires accessing from the first frame.

What types of frames are used in MPEG-1 to improve compression efficiency?

Predictive coded (P) frames and bidirectionally predictive coded (B) frames.

How do P frames differ from I frames?

P frames use motion-compensated prediction from the closest previous anchor frame, providing higher compression efficiency.

What is the role of B frames in MPEG-1 compression?

B frames use motion-compensated prediction from both the most recent and closest future anchor frames.

What is a Group of Pictures (GOP) in MPEG?

The smallest random access unit in the video sequence that includes at least one I frame.

What is the trade-off concerning I frames in MPEG?

The frequency of I frames must balance compression efficiency with random access convenience.

What is one advantage of using B frames in video sequences?

They allow for high compression by making use of both past and future frames for prediction.

What is indicated by the term 'anchor frames' in MPEG?

I and P frames are referred to as anchor frames because subsequent frames depend on them for prediction.

Explain 'display order' in the context of video sequences.

The sequence in which the video is presented to the user.

Describe the 'bitstream order' for frames in MPEG.

The order in which frames are processed for encoding in the stream, which may differ from display order.

In motion compensation, how does the search area vary?

The search area grows with the distance between the frame being encoded and the prediction frame.

What does DCT stand for in video compression?

Discrete Cosine Transform.

What role does quantization play in MPEG compression?

It reduces the precision of transform coefficients to decrease the amount of data transmitted.

How are rate control measures prioritized in the MPEG standard?

Bit rate reduction begins with B frames as they are non-essential for decoding other frames.

What is one limitation of prediction based solely on past frames when using B frames?

Prediction may be inaccurate during sudden changes, such as in TV advertisements.

What happens to B frames in the sequence in relation to future anchor frames?

B frames must be generated after the closest future anchor frame is available.

What is a common characteristic of video calls in videoconferencing concerning frame use?

Calls are set up, conducted, and terminated in a defined sequence.

How frequently should I frames occur in a GOP structure?

I frames should occur quite frequently to reduce viewer wait times for picture display.

What is the importance of quantization tables in MPEG compression?

Different quantization tables can be used for various frames and can be changed during encoding.

What is the main focus of the MPEG standard compared to H.261?

MPEG initially focused on digital storage and retrieval rather than real-time videophone applications.

What is the purpose of motion compensation in MPEG?

Motion compensation aims to reduce temporal redundancy by predicting and estimating motion between frames.

What factors can influence the selection of the GOP size?

Factors include the desired random access capability and the overall quality and compression efficiency of the video.

What is the role of the decoder in the MPEG framework?

The decoder reconstructs the video from the encoded bitstream, using anchoring frames for correct prediction.

How does the frame order impact video playback in MPEG?

Frame order affects how the video is displayed, as it may differ from the encoding or bitstream order.

What is a significant feature of B frames compared to P frames?

B frames can reference both past and future frames, providing more flexibility for prediction.

Why is rate control important in MPEG video streaming?

Rate control ensures a consistent quality of service and helps manage bandwidth utilization effectively.

What does 'temporal redundancy' refer to in video compression?

Temporal redundancy refers to the repeated information across frames that can be removed to save data.

How do I frames contribute to error recovery in video streaming?

I frames serve as reference points for recovery in case of errors, as they are self-contained frames.

What is the importance of using different motion vectors in MPEG?

Different motion vectors allow for more accurate representation of object movement, enhancing compression.

What challenges can arise with real-time encoding in MPEG?

Real-time encoding can introduce latency, requiring efficient processing capabilities and prioritization of frame