I’m in the midst of some heated emails with the manufacturer of the new MP3 player I installed in my car. The player plays back VBR-encoded MP3 files just fine, but the displayed time remaining is completely wrong. It’s apparent that the player is determining track length by reading the bit rate of the first frame (or frames) of the file and dividing that into the file size - the initial frame rate being 32kbps, as it is usually silence. This results in files reported as being 25-35 minutes long.
I maintain that the MP3 standard allows for each frame to have its own bitrate assigned to it, and that in making assumptions based on the initial frame, the player isn’t fully conforming to the MP3 standard. The manufacturer is claiming that VBR is in no way codified in the MP3 standard, and that I’m lucky the files even play back at all.
My reasoning is based on Wikipedia’s article on MP3s. Although largely accurate, Wiki can sometimes leave out important bits. Am I completely off the mark here, or is the manufacturer lying to get out of having to implement this fix?
I have to admit I’m completely ignorant on the subject of MP3 files, but regardless of the accuracy of Wikipedia, what makes you think the manufacturer is under any obligation to “implement this fix”?
Perhaps you could be influential in persuading them to add new functionality to their product in the next release, but it sounds to me like the product does what they designed it to do. The fact that it handles (partially) VBR files is an added bonus.
I don’t have much to add here, except that I’ve had my own problems with VBR and flash players, and I never thought that it might be the manufacturer’s obligation to make things work. Always work with constant bit rates… it might be my imagination, but they sound a little better too, even on players that get them right otherwise.
Because it’s advertised as an MP3 player. If setting individual bit rate per frame is part of the standard that defines what an MP3 file is (hence, this thread - I’d like to know if I’m right before pursuing this further), then their flat-out refusal to fix this lack of functionality, now or in the future, is unacceptable. It’s as if someone sells a player that “Plays CDs” except that it only plays odd-numbered tracks. Standards are standards, and if a company advertises its product as supporting one, with no footnote mentioning otherwise, it had better support that standard fully.
Variable bit rate is part of the MP3 standard, but displaying the correct time of the track is not. There is an unofficial tag that can be inserted in a track to tell the encoder the true length of the track but it is not part of the MP3 standard.
I forgot to add that as far as the player is concerned, what it must or must not do is determined by the language on the box and in the advertising and supporting materials. It is not determined by any format standards. If the player, for example, says “this player plays MP3 files” then all the manufuacturer has to show is that it can play some sort of MP3 file. You can’t legally assume it means that the player is fully compatible with every aspect of the format unless the player specifically says those exact words. Hence the expression, “Let the buyer beware.”
Hmmm… that’s interesting. To borrow from Alvis’ analogy… what would the situation be for a “CD player” that only played 3/4 of the tracks on a CD… or played some CDs or not others?? And would bad word of mouth hit something like that much worse than his MP3 player??
That doesn’t make sense… the point of VBR is to get better quality out of the same number of bits. A VBR file should always sound better than a CBR file with the same average bitrate, unless your encoder is broken or every frame of the file is equally complex.
As for the OP: the manufacturer is correct that the MP3 spec doesn’t say anything about measuring the length of a VBR file. Every frame can have its own bitrate, and every MP3 player should be able to play VBR files, but time display and seeking are separate problems.
However, if I were you, I’d return that player and get a better one, and let them know why. There is a de facto standard header that allows players to do time display and seeking for VBR files, and if this manufacturer has decided not to support it, they’re not being competitive. I have a JVC MP3 player in my car, and it works fine with VBR files.
Why does the player have to support that? Does the MP3 licensing program require that all devices adhere to a certain set of guidelines or anything like that? I didn’t think there was any product certificaton involved with using MP3, and that all that’s needed for a license is your willingness to pay. (Unlike, for example, stuff that’s designated “Designed for Windows”, “Plays for Sure”, “WHQL Certified” etc.).
As for the time thing… well, some players (like the iPod shuffle) don’t have time displays at all and the manufacturers don’t seem to care.
In the end, if it doesn’t do what you want it to do, just return it and get another product.