I figured it was about time to do a re-rendering quality loss test for MPEG-2. The topic of using MPEG-2 as source files for editing keeps popping up more and more often lately. I started with a basic uncompressed 4:4:4 image, added a bit of animation to it, and rendered a 1 second MPEG-2 file. This file was then used as the source for a second rendering, and so forth, through 99 generations.
I chose the standard DVD-Architect NTSC video stream template since this topic often comes up with respect to reusing video from DVDs. I left all settings for the Main Concept encoder set at the default with only two exceptions: field order was set to progressive and two-pass encoding was enabled. The list of settings is:
- Video type: DVD
- Frame rate: 29.970
- Width: 720
- Height: 480
- Aspect ratio: 4:3 Display
- I-frames: 15
- B-frames: 2
- Profile: Main Profile
- Level: Main Level
- Field order: Progressive only
- Video quality: 31 (High)
- Insert sequence header before every GOP: Yes
- Variable bit rate
- Two-pass: Yes
- Maximum (bps): 8,000,000
- Average (bps): 6,000,000
- Minimum (bps): 192,000
This should be pretty representative of most good quality MPEG-2 material.
The results are posted in http://www.vegasusers.com/testbench/files/generations/ and all begin with "mc-mpeg2-". I've included the actual .mpg files as well as .png stills of frame 15 of each clip. The stills may not be representative since the quality can vary greatly from frame to frame. They do show a steady progression of loss of quality though.
The file "mc-mpeg2-dvd-00-99.mpg" contains all the other .mpg files in one video clip. Please note that this is a re-rendering of the re-renders, so each clip is actually one generation higher than the number displayed. Clip "0" in this file is 4:4:4 uncompressed rendered to MPEG-2, so it is actually first generation. Clip "99" is 100th generation. This only applies to this one file. All the individual .mpg files are the generation specified by the file name.
I was impressed to see how well Main Concept's encoder holds up. Even the 9th generation apeared quite usable. Noticeable artifacts appeared at around generation 15. While i still don't condone using MPEG files as editing sources, it looks like they will survive a few generations unscathed.
I chose the standard DVD-Architect NTSC video stream template since this topic often comes up with respect to reusing video from DVDs. I left all settings for the Main Concept encoder set at the default with only two exceptions: field order was set to progressive and two-pass encoding was enabled. The list of settings is:
- Video type: DVD
- Frame rate: 29.970
- Width: 720
- Height: 480
- Aspect ratio: 4:3 Display
- I-frames: 15
- B-frames: 2
- Profile: Main Profile
- Level: Main Level
- Field order: Progressive only
- Video quality: 31 (High)
- Insert sequence header before every GOP: Yes
- Variable bit rate
- Two-pass: Yes
- Maximum (bps): 8,000,000
- Average (bps): 6,000,000
- Minimum (bps): 192,000
This should be pretty representative of most good quality MPEG-2 material.
The results are posted in http://www.vegasusers.com/testbench/files/generations/ and all begin with "mc-mpeg2-". I've included the actual .mpg files as well as .png stills of frame 15 of each clip. The stills may not be representative since the quality can vary greatly from frame to frame. They do show a steady progression of loss of quality though.
The file "mc-mpeg2-dvd-00-99.mpg" contains all the other .mpg files in one video clip. Please note that this is a re-rendering of the re-renders, so each clip is actually one generation higher than the number displayed. Clip "0" in this file is 4:4:4 uncompressed rendered to MPEG-2, so it is actually first generation. Clip "99" is 100th generation. This only applies to this one file. All the individual .mpg files are the generation specified by the file name.
I was impressed to see how well Main Concept's encoder holds up. Even the 9th generation apeared quite usable. Noticeable artifacts appeared at around generation 15. While i still don't condone using MPEG files as editing sources, it looks like they will survive a few generations unscathed.