Poor Quality Video Burning Disk Image

[FredT]

I've used "Save to disk image" and burned the image fairly often when I have material that is just a little bit larger than will normally fit and let Toeat do the extra compression (Toast says quality will be "Excellent"). Even then I see some degradation in video quality from what I see from the disk image. Today I burned a disk that required 25% compression, quality to be "Very good". What I dsicovered was that large part of the disk have video that has largem, blocky pixels. I used Toast 8.01. Is there anything I should check? Quality of the disk image was very good. Thanks.

[FredT]

Today I stepped back to version 8.0 and burned another disk, with the same result. Next I dropped one of the five episodes I was burning. The remaining four episodes still would not fit, so I again made a disk image and then burned it. This time the compression required was much less, about 12%, with an anticipated quality of excellent. Indeed the resulting diak was satisfactory, not up to the quality of the disk image, but without the severe blocking that I saw in the previous disk. So to summarize, what Toast said would be "Very good" quality was totally unsatisfactory, while what it said would be "Excellent" was satisfactory. Can anyone comment on these reults? Is this what I should expect from Toast when burning a disk image? Thanks...

[tsantee]

I'm curious about what the audio format is that's with those videos and the total length of all the videos on the disc. IF the audio is PCM there is much less space available on the disc for the video than with the other audio formats. Toast only compresses the video, not the audio, so a 25% overall calculation would actually be a very much higher percentage compression of the video portion. The "Excellent" or "Very Good" judgements presume the disc has AC3 audio.

 

Even if the source audio is AC3 or MPEG, if the video is already at a low bit rate then a 25% compression can be severe. For example, if your DVD had 4 hours of video and it needed 25% compression to fit a single-layer disc then the video bit rate is very low.

 

My understanding is that Toast doesn't know if the result will be excellent or very good or fair. The Roxio engineers assigned those terms to different percentages of overall compression with the assumption that the source video has a fairly high average bit rate. Taking 25% from a 3 mbps video bit rate will be much more severe to picture quality than taking 25% from a 7 mbps video.

 

To summarize, trust what you see is working or not working for you rather than Toast's judgements. If you have a lot of video on the disc or are using PCM audio don't plan to do much additional compression without sacrificing picture quality.

[FredT]

I'm curious about what the audio format is that's with those videos and the total length of all the videos on the disc.

I really don't know much about the various formats and such. These are 24-minute programs recoded using EyeTV's highest setting. Toast says the vcideo is MPEG-2 and the audio is MPEG-1. My first attempt was with 5 episodes, total of 5.5 MB. The second try with four shows was just 4.4 MB.

 

Thanks for the information.

[tsantee]

I really don't know much about the various formats and such. These are 24-minute programs recoded using EyeTV's highest setting. Toast says the vcideo is MPEG-2 and the audio is MPEG-1. My first attempt was with 5 episodes, total of 5.5 MB. The second try with four shows was just 4.4 MB.

 

Thanks for the information.

In your case I would expect the five episodes to look very good when additionally compressed to fit a a single-layer disc. My previous rationale doesn't apply here. I have no explanation for your picture-quality problem.

 

If you record at EyeTV's Standard (2-hour) setting the five titles may actually fit the disc without any or with only a very little additional compression. I recommend using an EyeTV setting that best matches what you want for the final DVD.