{"action":"created","issue":{"url":"https://api.github.com/repos/bmcfee/librosa/issues/341","repository_url":"https://api.github.com/repos/bmcfee/librosa","labels_url":"https://api.github.com/repos/bmcfee/librosa/issues/341/labels{/name}","comments_url":"https://api.github.com/repos/bmcfee/librosa/issues/341/comments","events_url":"https://api.github.com/repos/bmcfee/librosa/issues/341/events","html_url":"https://github.com/bmcfee/librosa/issues/341","id":151846317,"number":341,"title":"missing 2^j factors in cqt and hybrid_cqt","user":{"login":"lostanlen","id":3943142,"avatar_url":"https://avatars.githubusercontent.com/u/3943142?v=3","gravatar_id":"","url":"https://api.github.com/users/lostanlen","html_url":"https://github.com/lostanlen","followers_url":"https://api.github.com/users/lostanlen/followers","following_url":"https://api.github.com/users/lostanlen/following{/other_user}","gists_url":"https://api.github.com/users/lostanlen/gists{/gist_id}","starred_url":"https://api.github.com/users/lostanlen/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/lostanlen/subscriptions","organizations_url":"https://api.github.com/users/lostanlen/orgs","repos_url":"https://api.github.com/users/lostanlen/repos","events_url":"https://api.github.com/users/lostanlen/events{/privacy}","received_events_url":"https://api.github.com/users/lostanlen/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":9,"created_at":"2016-04-29T11:33:06Z","updated_at":"2016-04-29T15:48:35Z","closed_at":null,"body":"Hi,\r\nWith @CarmineCella we've tried running the CQT on synthetic sounds, such as white noise (`np.random.randn`) as well as Diracs.\r\nIt looks like the `cqt` function, with relies on the pyramid algorithm of Schoerkuber and Klapuri, is not appropriately scaled in magnitude across octaves.\r\n\r\nBelow is the code to compute the CQT of a Dirac and the corresponding figure:\r\n\r\n```python\r\nimport librosa\r\nimport numpy as np\r\nx = np.zeros(32768)\r\nx[16384] = 1.0\r\nsr = 22050.0\r\nc = librosa.cqt(x, sr=sr)\r\nlibrosa.display.specshow(c)\r\n```\r\n\r\n![cqt_dirac](https://cloud.githubusercontent.com/assets/3943142/14914832/178b1d5a-0e0e-11e6-98f2-2f87c4e8ff89.png)\r\n\r\nAm I mistaken to think that the magnitudes should stay equal across octaves instead ?\r\n"},"comment":{"url":"https://api.github.com/repos/bmcfee/librosa/issues/comments/215770250","html_url":"https://github.com/bmcfee/librosa/issues/341#issuecomment-215770250","issue_url":"https://api.github.com/repos/bmcfee/librosa/issues/341","id":215770250,"user":{"login":"bmcfee","id":1190540,"avatar_url":"https://avatars.githubusercontent.com/u/1190540?v=3","gravatar_id":"","url":"https://api.github.com/users/bmcfee","html_url":"https://github.com/bmcfee","followers_url":"https://api.github.com/users/bmcfee/followers","following_url":"https://api.github.com/users/bmcfee/following{/other_user}","gists_url":"https://api.github.com/users/bmcfee/gists{/gist_id}","starred_url":"https://api.github.com/users/bmcfee/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/bmcfee/subscriptions","organizations_url":"https://api.github.com/users/bmcfee/orgs","repos_url":"https://api.github.com/users/bmcfee/repos","events_url":"https://api.github.com/users/bmcfee/events{/privacy}","received_events_url":"https://api.github.com/users/bmcfee/received_events","type":"User","site_admin":false},"created_at":"2016-04-29T15:48:35Z","updated_at":"2016-04-29T15:48:35Z","body":"Okay, I see two issues in this thread then.\r\n\r\n1. Hybrid cqt scaling is inconsistent. This is easy to fix.\r\n2. High frequency cqt is lossy at high hop lengths. This is fixable by using redundant bases, which we probably should do in preparation for #165. However, it requires substantial changes to all cqt-related functions.\r\n\r\nI think we can do 1 for the next minor release 0.4.3 and punt the redundant basis implementation to 0.5.\r\n\r\nSound good?"}}