21326 2013-03-18 23:31:52 +0000 Encourage x-fades or at least v-fades. 2013-04-08 21:19:45 +0000 1 1 1 Unclassified HTML WG Media Source Extensions unspecified PC Windows NT RESOLVED FIXED P2 normal --- 1 pal adrianba acolwell mike public-html-media public-html-bugzilla oldest_to_newest 84590 0 pal 2013-03-18 23:31:52 +0000 "3.5.9 Audio Splice Frame Algorithm" suggests adding a "silence frame" if x-fading is not available. This will lead to extremely harmful artifacts if the signal in either the track buffer or append segment contains any energy. The specification can instead recommend v-fades, where each of the track buffer and append segment signals are independently faded to 0 around the splice point, as a simpler alternative to x-fades where overlap between the two signals is used. 84621 1 acolwell 2013-03-19 15:00:40 +0000 The case where crossfading is not supported is there to handle cases where the UA may not have access to the baseband signal such as harware decoding and or protected content. If an implementation is going to implement the v-fades you suggest it might as well just implement the crossfade since the necessary modifications to the media engine would be similar. At best a non-normative note could be added to this section suggesting fades to 0, but I don't expect implementations to actually do this given that this only would apply to cases where fades to zero were possible and significantly less complex to implement then the actual crossfade. 85579 2 pal 2013-04-04 19:37:40 +0000 (In reply to comment #1) Well, implementations can always do the wrong thing :) but the specification should recommend the right thing. In 99% of scenarios, the right thing is never to insert silence (zeroes) in an audio stream without a fade, or at the very least without waiting for the signal to cross zero. Fades to/from zero (or waiting for a zero-crossing) are sometimes easier than cross-fade since no overlap of content is required. 85741 3 acolwell 2013-04-08 21:19:45 +0000 Change committed. https://dvcs.w3.org/hg/html-media/rev/f7f2b7226543 Added a note indicating that implementations may choose to apply fades to/from silence sections. I am keeping this non-normative until we have implementation experience that shows that implementing such fades is possible in a majority of cases when hardware decoders and secure decode pipelines are being used.