| Fumanchu said: @ Guiding Light Thx for your info, this topic has been long debated and it seems like there's been a lot of misinformation and conflicting sources regarding read speed/seek time comparisons. I don't mean to be cynical but there's a couple of concerns that I don't understand and maybe if I can 'pick your brains' now we can put the issue to bed once and for all. 1. After being force fed the quote from beyond3d for so long - I was wondering if you could help me understand how exactly the 360 reads DL at the same speed as SL? 2. Is the read speed then the quoted SL speed or something else? - "12x DVD-Rom Drive SL (9.25MB/S-15.85MB/s(AVG ~8x(10.57MB/s)" (obviously that average doesn't account for optimisation). |
Pretty simple really...
12x is it's official maximum speed when reading a dual layer disc. It would only reach this speed when reading data on the very outer edge of the disc. So, since the outer 1GB (roughly) is never used it would reach a maximum speed of (educated guess) 11.1\11.2x (note I haven't done an actual sum to achive this because the CAV doesn't increase\decrease reading speed at a linear amount.
So...roughly speaking...
Starts reading the inner ring at around 5x -> 11x (then changes to the 2nd layer and reads backwards).
If you read the disc with a tool like Nero CD-DVD speed, the speed would appear as an "arc"...
Most Xbox 360 games are around 5GB, this game data is placed after the dummy\padding data, also to further optimise, movies\fmv are placed straight after the dummy\padding...Stuff that needs to go with a "now loading" screen is placed as far away from the centre as possible...
This is why games like Soul Calibur 4, Street Fighter 4 etc have very similar loading times to the PS3 even though the PS3 has an install. You see, quoting the average read speed for the Xbox 360 is very misleading due to the CAV reading, do people really think the developers are so stupid that they would place data that needs to be read as quickly as possible closer to the inner ring of the disc (rhetorical question).
To add to this, you will see that raw game assets (excluding movies) don't actually take up that much space so for games that are 6.8GB (maximum). They normally have a lot of movie data which would be placed in the centre.
Not sure if it needs to be said, but the movie data read speed doesn't matter since it only needs to be read fast enough to not skip. A DVD running at 3.3x is fast enough to display 1080p bluray at highest quality possible.
....Oh to answer your actual 2. question, the answer is yes. However you have to take into account that the last 1GB isn't used on the disc so it will take the average down a little I have no exact number, but you could easily test this yourself by burning a DL DVD-\+R with 7GB of data, then using Nero CD-DVD speed to produce a graph setting the maximum read speed to 12x. Most DVD-ROM pc drives these days read at 12x for DL media. (12x reached at outer edge)
