{"action":"created","issue":{"url":"https://api.github.com/repos/gpac/gpac/issues/23","labels_url":"https://api.github.com/repos/gpac/gpac/issues/23/labels{/name}","comments_url":"https://api.github.com/repos/gpac/gpac/issues/23/comments","events_url":"https://api.github.com/repos/gpac/gpac/issues/23/events","html_url":"https://github.com/gpac/gpac/issues/23","id":52630874,"number":23,"title":"[DASH] Bitstream switching between Representations that use different codecs.","user":{"login":"vladimir-kazakov","id":3518844,"avatar_url":"https://avatars.githubusercontent.com/u/3518844?v=3","gravatar_id":"","url":"https://api.github.com/users/vladimir-kazakov","html_url":"https://github.com/vladimir-kazakov","followers_url":"https://api.github.com/users/vladimir-kazakov/followers","following_url":"https://api.github.com/users/vladimir-kazakov/following{/other_user}","gists_url":"https://api.github.com/users/vladimir-kazakov/gists{/gist_id}","starred_url":"https://api.github.com/users/vladimir-kazakov/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/vladimir-kazakov/subscriptions","organizations_url":"https://api.github.com/users/vladimir-kazakov/orgs","repos_url":"https://api.github.com/users/vladimir-kazakov/repos","events_url":"https://api.github.com/users/vladimir-kazakov/events{/privacy}","received_events_url":"https://api.github.com/users/vladimir-kazakov/received_events","type":"User","site_admin":false},"labels":[],"state":"closed","locked":false,"assignee":null,"milestone":null,"comments":8,"created_at":"2014-12-22T08:59:54Z","updated_at":"2015-02-24T10:38:07Z","closed_at":"2015-01-06T15:26:43Z","body":"Hi!\r\n\r\nWhile creating DASH media using MP4Box (GPAC rev 5572), I noticed a warning that says \"[DASH]: Couldnt merge AVC|H264 SPS from different files (same SPS ID used) - different sample descriptions will be used\". Also, by looking at the code and by checking the MPD, I noticed that bitstream switching is turned off in this case: https://github.com/gpac/gpac/blob/25a10ffec1af2431a708d3b0ca4133c228cc4787/src/media_tools/dash_segmenter.c#L2437\r\n\r\nMy media consists of 2 video (v) and 1 audio (a) stream (http://1drv.ms/1xDsl27):\r\n1.v) 360p using Constrained Baseline profile and level 3.0.\r\n2.v) 720p using High profile and level 3.1.\r\n1.a) AAC-LC.\r\n\r\nSo, what triggers this behavior (and warning) is the fact that I'm using different codecs for different video Representations.\r\n\r\nBut it seems that something is wrong here.\r\n1) DASH-AVC/264 Interoperability Points v2.0 (and other versions) does not require Representations in one specific AdaptationSet to use the same codec. (This case is not even mentioned there.)\r\n2) ISO/IEC 23009-1 (2nd edition) (DASH standard) also does not have such a requirement, but it additionally mentions in 4.3 that \"Clients may ignore Representations that rely on codecs or other rendering technologies they do not support or that are otherwise unsuitable\".\r\n\r\nIn other words, only media players (Clients) must decide whether they're going to switch to specific (supported) streams. So, bitstream switching must not be disabled by default, if different codecs are used.\r\n\r\nAlso, speaking of the warning itself, it seems wrong or misleading (although I must say that I don't know much about SPS NAL units). Why MP4Box is trying to merge SPSs? Since different profiles and levels are used, it should be OK that SPSs are different, isn't it? And if SPSs \"couldn't be merged\", then why the \"same SPS ID used\"?"},"comment":{"url":"https://api.github.com/repos/gpac/gpac/issues/comments/75733884","html_url":"https://github.com/gpac/gpac/issues/23#issuecomment-75733884","issue_url":"https://api.github.com/repos/gpac/gpac/issues/23","id":75733884,"user":{"login":"jeanlf","id":7303785,"avatar_url":"https://avatars.githubusercontent.com/u/7303785?v=3","gravatar_id":"","url":"https://api.github.com/users/jeanlf","html_url":"https://github.com/jeanlf","followers_url":"https://api.github.com/users/jeanlf/followers","following_url":"https://api.github.com/users/jeanlf/following{/other_user}","gists_url":"https://api.github.com/users/jeanlf/gists{/gist_id}","starred_url":"https://api.github.com/users/jeanlf/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/jeanlf/subscriptions","organizations_url":"https://api.github.com/users/jeanlf/orgs","repos_url":"https://api.github.com/users/jeanlf/repos","events_url":"https://api.github.com/users/jeanlf/events{/privacy}","received_events_url":"https://api.github.com/users/jeanlf/received_events","type":"User","site_admin":false},"created_at":"2015-02-24T10:38:07Z","updated_at":"2015-02-24T10:38:07Z","body":"thanks for the files. this should now be fixed (also added an error message in case one wants bs switching in ondemand profile)"}}