视频传输4：MPEG4, H.263, and H.263+

Experimental Setup

Our Encoding Approach

MPEG4, H.263, and H.263+

For each video we grabbed the (uncompressed) YUV information with (Version 0.15.10) and stored it on disk. The YUV information was grabbed at a frame rate of 25 frames/sec in the QCIF format.

The YUV frame sequences were used as input for both the MPEG-4 encoder and the H.263 encoder.

We emphasize that we did not encode in real-time; thus there was no encoder bottleneck.

For each video we encoded the YUV information into an MPEG-4 bit stream with the MOMUSYS MPEG-4 video software; we encoded each video at three different quality levels: low, medium, and high.

We encoded the uncompressed YUV information into a H.263/H.263+ bit stream with the tmn encoder (Version 2.0/3.2); we encoded each video at four different target bit rates: (1) 16 kbit/sec, (2) 64 kbit/sec, (3) 256 kbit/sec, and (4) Variable Bit Rate (VBR), i.e., without setting a target bit rate.


H.261

For each video we grabbed the (uncompressed) PPM information with (Version 0.15.10) and stored it on disk. The PPM information was grabbed at a frame rate of 25 frames/sec in the QCIF format. Afterwards we splitted the PPM in three parts: Y, U, and V.

We encoded the uncompressed Y, U, and V information into a H.261 bit stream with the p64 encoder; we encoded each video at three different target bit rates: (1) 64 kbit/sec, (2) 256 kbit/sec, and (3) Variable Bit Rate (VBR), i.e., without setting a target bit rate.

We refer to the available for details on the encoding procedure.