Gravure-News

[franz99]

Bien sûr en cas de gravure la précaution à prendre
- est de d'abord bien choisir ses médias vierges
- ensuite de s’assûrer que la 1ère gravure faite sur un MID code donné
et dans certaines conditions "alchimiques" bien précises [graveur + firmware + vitesse]
est bien dans la norme ECMA,
voir:
« Qualité partie 1 - les erreurs PI / PO »
http://www.gravure-news.com/html/arts/17/page01.php
et peut être lue sur une ou plusieurs platines de salon.
Je ne parle pas ici du problème du « book type » DVD-ROM dont l'absence empêchait le démarrage de la lecture sur certaines platines maintenant anciennes.


Personne n’a envie après avoir gravé un DVD vidéo
ou même après avoir acheté un DVD vidéo pressé
de s’asseoir pendant des heures afin de s’assurer que celui-ci est parfaitement lisible sur une platine DVD de salon.
De plus les platines de salon sont d’une sensibilité inégale.

Une des méthodes les plus couramment appliquées est de skipper d’un chapitre à l’autre pour en jouer le début, or justement en cas de problème de lecture au milieu d’un chapitre c’est souvent (lorsqu'elle ne "freeze" pas)
ce que la platine fait d’elle même: elle saute au début du chapitre suivant .

[franz99]

Voici concernant ce sujet les principaux extraits d’un débat récent sur cdfreaks :
« Quickest way to test a movie by watching... »
http://club.cdfreaks.com/showthread.php?t=193603

arif1979:
« Obviously I don't feel like sitting an hour or two to actually watch a movie that I'm simply testing to make sure it doesn't skip or freeze.
I don't think fast forwarding works either because I think that sometimes won't show where it would freeze.
Is there any easier way to "scan" a movie to make sure there are no problems? (Since tests on the computer don't always show whether the DVD will still play fine on the dvd player) »

Arachne:
« A transfer rate test on your pickiest reader in CD-DVD Speed (under the "Benchmark" menu) is a good test to run along with a quality scan.
If there are any big speed drops, I'd consider the disc suspect at least. »

Pedxingx:
« I talked to a software video editing company which encoutered a similar problem. Their solution was to hire an army of QA people to sit and watch TV all day.
I forgot about what Arachne said. A high speed transfer rate test can give a loose correlation about the quality of the disk too.
I remember testing a whole bunch of DVDs I bought on the web. Since I couldn't watch all of them before the return policy expried, I did a transfer rate test on them and watched the ones where the transfer rate tests showed problems. In the end, the marginally bad discs died of DVD rott within a year »

Koba:
« Some standalone players freeze while fastforwarding and during playback of a movie if the disc is severely damaged.
Others will just skip the damaged part while fastforwarding and freeze during normal playback.
Also some other players will just skip any damaged part during fastforward and normal playback. »

Franksoy:
« If the question is about the media/burn, I'll backup Arachne:
a perfect TRT with no speed drops, performed in a non-LiteOn drive
(they're so good readers that they can be too forgiving),
almost 100% guarantees that the disc will play fine »

Why "almost"? Because if you use discs with not-so-high reflectivity (TYG02, some CMC MIDs...), you may still have reading issues in some picky standalone player even when the disc itself is perfectly fine. »

[franz99]

Le débat semble donc touner autour du fait de savoir si un TRT (transfert rate test)
qui dure entre 4 et 5 minutes pour un DVD simple couche
est une méthode suffisante ou non ?


Et je demande pourquoi un scan à balayage rapide (environ 1 minute)
ne le compléterait pas utilement,
voir:
« Scan à balayage rapide (DVD speed) »
http://forum.gravure-news.com/scan-a-ba ... t23437.htm

[franz99]

Les scans d'erreurs comparés aux TRT (test du taux de transfert):
« Quality Scan vs Transfer Rate Test »
http://club.cdfreaks.com/showthread.php?t=167693

IMO there is enough empirical evidence to support the idea that PIE/PIF scanning is unreliable to sort out good discs from coasters,
but it's not as simple as replacing PIE/PIF scanning with transfer rate tests,
as the latter are just as dependant on the drive used than PIE/PIF scanning is.
And I think that PIE/PIF scanning is under suspicion mainly because of the discrepancies in errors reporting among drives.


The most interesting point that you rise, sugarmommyst, is this one IMO:
Quality scan is good for comparing between 2 good media but cannot tell if a disc is readable or if it will coaster.

Actually it's been common practise among advanced users and mods, here, to perform BOTH tests. That's also what reviewers (at least the serious ones) do when testing drives and media. Both tests give indications.