Slideshow from 10 JPGs - Smaller if created as "Music Compilation"
jamesreese
wrote on 5/25/2004, 10:31 AM
Comments
SonySDB
wrote on 5/25/2004, 11:53 AM
Picture compilation: 10 * 5 seconds * 8 Mbps = 50 MB. When you account for the audio, that's why the picture compilation is 52.4 MB.
MPEG2 is rendered in Vegas: If you used the "DVD Architect NTSC video stream" template to render the MPEG2 file, it uses variable bit rate encoding with a maximum of 8 Mbps and an average of 6 Mbps. And because it's encoding stills, the encoder probably didn't take advantage of the 6 Mbps average it is alloted.
Music compilation: Music compilations are optimized to handle video's that are shorter than the duration of the slide. That's why its estimated size is less than the picture compilation. Also, it shows a smaller estimated size than DVDA1 because of the lack of precision in this specific calculation in DVDA2. We will look into fixing this. Thanks.
MPEG2 is rendered in Vegas: If you used the "DVD Architect NTSC video stream" template to render the MPEG2 file, it uses variable bit rate encoding with a maximum of 8 Mbps and an average of 6 Mbps. And because it's encoding stills, the encoder probably didn't take advantage of the 6 Mbps average it is alloted.
Music compilation: Music compilations are optimized to handle video's that are shorter than the duration of the slide. That's why its estimated size is less than the picture compilation. Also, it shows a smaller estimated size than DVDA1 because of the lack of precision in this specific calculation in DVDA2. We will look into fixing this. Thanks.
jamesreese
wrote on 5/25/2004, 12:59 PM
JSWTS
wrote on 5/25/2004, 2:45 PM
The limitation in number of jpgs in DVD-A is going to be primarily based on the total duration of your pics, and the bitrate that they are encoded at (8Mbps), rather than a specific number of photos. The audio component, assuming you are using compressed ac3 audio, will take up very little comparative space. You can have about 70 minutes (again, using compressed audio and a few basic menus) of material on a standard, single sided recordable disc if you are encoding at 8Mbps. You would have to do the math to figure out how many pictures you could fit on a disc--ie 70 minutes times 60 secs would be 4200 seconds on a disc. If you divide that by the number of seconds you will display each slide, you will get the ~ number of slides you could use. The longer they are displayed, the fewer you can use. If you display them 5 seconds, then you could have ~840 slides (4200/5). If you use transitions, then they will take up some extra time as well, and in turn, decrease the number of slides you can use.
The reason there is a "99" slide limit is that you can only have 99 chapters in a title set. You can add more than 99 slides in a single picture compilation in DVD-A 2, you just won't have anymore chapter marks beyond 99. You can create several picture compilations, each with 99 slides, and link the end action to the next slide collection to give it a seamless appearance (and the ability to navigate between all of your slides).
I personally think the way DVD-A 2 accomplishes slides shows wastes disc space. It essentially treats it as a video stream, and encodes it as such. Many other apps that allow for slideshows do it differently. They encode a single "I" frame, and just instruct the dvd player how long the pic show be displayed. For example, if you have a single slide you want to display for 5 sec's, DVD-A 2 will encode it as 5 seconds of video (about 150 frames--5sec's times 29.97 fps). If it is encoded as a single "I" frame (nearly 149 frames less), it would just be displayed for 5 seconds. By doing it this way ("I" frame only), you can add slide shows to video discs without worrying as much about running out of space.
jim
The reason there is a "99" slide limit is that you can only have 99 chapters in a title set. You can add more than 99 slides in a single picture compilation in DVD-A 2, you just won't have anymore chapter marks beyond 99. You can create several picture compilations, each with 99 slides, and link the end action to the next slide collection to give it a seamless appearance (and the ability to navigate between all of your slides).
I personally think the way DVD-A 2 accomplishes slides shows wastes disc space. It essentially treats it as a video stream, and encodes it as such. Many other apps that allow for slideshows do it differently. They encode a single "I" frame, and just instruct the dvd player how long the pic show be displayed. For example, if you have a single slide you want to display for 5 sec's, DVD-A 2 will encode it as 5 seconds of video (about 150 frames--5sec's times 29.97 fps). If it is encoded as a single "I" frame (nearly 149 frames less), it would just be displayed for 5 seconds. By doing it this way ("I" frame only), you can add slide shows to video discs without worrying as much about running out of space.
jim
jamesreese
wrote on 5/25/2004, 7:50 PM
johnmeyer
wrote on 5/25/2004, 8:02 PM
It would appear that the best way to minimize file size for a non-audio JPG slide show is to create a "music compilation" with JPGs only.
Read Sony's response carefully. If the different file sizes you are reporting are simply the estimates that DVDA provides, these estimates are completely and utterly useless. They are bogus. They are incorrect. They are not worth the pixels they are drawn with.
You will have to actually render and prepare each test project and then look at the size of all the VOB and IFO files for each project. Only then can you tell if there are really any significant differences. Unless DVDA can perform the trick that JSWTS talked about (only having a single I frame and then telling the player to play that for a long time), I would bet that each method of creating the slide show is going to produce the same file size.
However, that is just a guess. You will have to do a test render/prepare to really know for sure.
Read Sony's response carefully. If the different file sizes you are reporting are simply the estimates that DVDA provides, these estimates are completely and utterly useless. They are bogus. They are incorrect. They are not worth the pixels they are drawn with.
You will have to actually render and prepare each test project and then look at the size of all the VOB and IFO files for each project. Only then can you tell if there are really any significant differences. Unless DVDA can perform the trick that JSWTS talked about (only having a single I frame and then telling the player to play that for a long time), I would bet that each method of creating the slide show is going to produce the same file size.
However, that is just a guess. You will have to do a test render/prepare to really know for sure.
JSWTS
wrote on 5/26/2004, 7:33 AM
You might have happened upon a solution, because it does look like DVD-A treats an image associated with audio in a music compilation as a single "I" frame. I haven't tried it, but the numbers look about right.
Unfortunately it requires you to have no audio.
Jim
Unfortunately it requires you to have no audio.
Jim
johnmeyer
wrote on 5/26/2004, 8:53 AM
I wonder if there would be a rendering problem if the erroneous "forecasted" size of a project exceeded the DVD capacity, even when in reality it might actually fit.
No, don't worry. DVDA's estimates are simply brain-dead. The numbers have virtually no meaning whatsoever, and are certainly no indication of burn quality.
Thanks for doing the actual burn tests and then reporting the results. That is really helpful. It sure would be useful if Sony used more helpful terms to describe what "Music Compilation" and "Picture Compilation" really do. You have just discovered an amazingly useful feature, but there is no mention of it anywhere. Likewise, I found that Music Compilation actually combines separate video MPEG files into one VOB, allowing the video to flow uninterrupted from one MPEG to the next, and without forcing the player to hunt for a new titleset. This means I no longer have to join MPEG files together prior to importing to DVDA. Just like what you discovered, there is no mention of this feature anywhere in the literature either.
No, don't worry. DVDA's estimates are simply brain-dead. The numbers have virtually no meaning whatsoever, and are certainly no indication of burn quality.
Thanks for doing the actual burn tests and then reporting the results. That is really helpful. It sure would be useful if Sony used more helpful terms to describe what "Music Compilation" and "Picture Compilation" really do. You have just discovered an amazingly useful feature, but there is no mention of it anywhere. Likewise, I found that Music Compilation actually combines separate video MPEG files into one VOB, allowing the video to flow uninterrupted from one MPEG to the next, and without forcing the player to hunt for a new titleset. This means I no longer have to join MPEG files together prior to importing to DVDA. Just like what you discovered, there is no mention of this feature anywhere in the literature either.