Hi Marco, I think before synchronizing the supported formats in Gaia and Gecko, maybe Gecko can first sync with DeviceStorage.properties, nsMediaSniffer and nsExternalHelperAppService.
Music app uses MediaDB which integrates the DeviceStorage API and the IndexedDB API, and DeviceStorage will return files to be parsed with metadata parser in Music app. Because DeviceStorage returns formats base on DeviceStorage.properties, if we already know some formats are not supported in Gecko, we shouldn't pass them to the metadata parser, also MediaDB will not record them and not to mention they will not be listed in Music app. And for the known supported formats, nsExternalHelperAppService should not block them, right? If we filter out the unsupported formats with the first step, it's still possible that some supported formats/containers with unsupported encodings will be recorded in MediaDB, and when Music app tries to play them, we might still encounter the error of "Warning: HTTP "Content-Type" of "audio/xxx" is not supported." But does using only the logic of audio.canPlayType() to judge files can playable or not solve this problem? I guess probably, but the metadata parsing time will take even longer because we have to try to decode every files before we parse the metadata, I am not sure how long it takes to decode one audio file, but certainly it saves time if we parse files without decoding them first. I am thinking that maybe error handling ui is a good choice if we cannot guarantee the so-called "audio" files listed in Music app can be playable or not. Cheers, Dominic ----- Original Message ----- From: "Marco Chen" <[email protected]> To: "dev-b2g" <[email protected]> Cc: "Paul Adenot" <[email protected]> Sent: Friday, May 3, 2013 6:46:00 PM Subject: [b2g] [Media] The media filter between Gaia - music app and Gecko - nsMediaSniffer & nsExternalHelperAppService Hi all, Even this topic seems to be related to media (dev-media) but according it also related to Gaia and b2g I post it to dev-b2g first. Issue: Currently, we met a bug about some files which can be listed by Music app but can't play by Gecko. The main reason is that there are two media sniffer mechanism performed by Gaia and Gecko separately. Detail: Gaia: Music app used media sniffer mechanism from metadata.js which will try to parse metadata by itself in first. If first step is failed then fall into Gecko's mechanism (audio.canPlayType()) Gecko:nsMediaSniffer implemented metadata parsing for some media type too. If nsMediaSniffer is failed then check into nsExternalHelperAppService's mimetype entries. So if Gaia's metadata.js is implemented with different way then Gecko's then issue mentioned by this mail will be occurred. Discussion Item: Do we really need Gaia to do filter by itself or just to use Gecko's mechanism (audio.canPlayType()) is enough? Then this way can avoid the in-consistent filter capability between Gaia & Gecko. Thanks, Sincerely yours ------------------------------------- Marco Chen System Engineer in Firefox OS Mozilla Taiwan Tel: +886-2-87861100 # 352 mail: [email protected] _______________________________________________ dev-b2g mailing list [email protected] https://lists.mozilla.org/listinfo/dev-b2g _______________________________________________ dev-b2g mailing list [email protected] https://lists.mozilla.org/listinfo/dev-b2g
