diff options
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/playlists.md | 27 |
1 files changed, 19 insertions, 8 deletions
diff --git a/docs/playlists.md b/docs/playlists.md index 45e36fe..232eae5 100644 --- a/docs/playlists.md +++ b/docs/playlists.md @@ -1229,14 +1229,25 @@ reads §15.1 as more than it is. `UPLOAD_CHUNK_SIZE` is 48 KB going up while `CHUNK_SIZE` is 1 MB coming down, which is the same constraint seen from both ends. - So `USER_BLOB_BODY_MAX = 1 MB` is a cap the client can never reach. Measured - rather than derived: a thousand tracks with varied metadata seal to **53 276 - bytes**, and each further track costs about 50, so one playlist tops out near - **1200 tracks**. (An earlier draft of this paragraph said 225, by reading §4's - ~270 bytes a track *raw* as the *sealed* figure. `test_playlist_store.py` - measures it now, and fails if a thousand tracks stop fitting.) Reading is - unaffected — a node answers with a whole body, and 256 KB is measured coming - back. + So `USER_BLOB_BODY_MAX = 1 MB` is a cap the client can never reach. How many + tracks 62 KB is depends entirely on how much the metadata repeats, because + repetition is all deflate has to work with — so it was measured at both ends + rather than derived: + + | a library where… | per track | one playlist tops out at | + |---|---|---| + | artists, albums and folders recur | ~50 B | ~1200 tracks | + | nothing repeats at all | ~91 B | ~660 tracks | + + Real libraries sit near the first row — an album contributes a dozen tracks + sharing three fields — but the sentence shown to a reader has to hold in the + second, so it says **500**. (Two earlier drafts of this paragraph were wrong + in both directions: 225, from reading §4's ~270 bytes a track *raw* as the + *sealed* figure; then 1200, from a fixture with fourteen words of vocabulary, + which measured deflate's opinion of its own regularity. Both numbers are now + measured by `test_playlist_store.py`, which fails if either stops holding.) + Reading is unaffected — a node answers with a whole body, and 256 KB is + measured coming back. **Taken:** the client caps itself at 62 KB of sealed body, checked after sealing because compression makes a track count a poor guide to a blob length. |