Opened 13 years ago

Last modified 11 years ago

#10658 closed Developer Task

Allow partial AVFRingBuffer reads — at Version 4

Reported by: danielk Owned by: danielk
Priority: minor Milestone: 0.28
Component: MythTV - General Version: Master Head
Severity: medium Keywords:
Cc: Ticket locked: no

Description (last modified by danielk)

Traditionally we've always had RingBuffer::Read() return the number of bytes requested unless we are at the end of the file. But this blocks libav which expects this the read to complete fairly quickly even if it is a blocking read. Instead we should block for only a short time waiting for more data and then return what data we do have as long as we have at least 1 byte of data.

Change History (7)

Changed 13 years ago by danielk

Attachment: 10658-v1.patch​ added

Initial patch

comment:1 Changed 13 years ago by danielk

Owner: set to danielk
Status: new → accepted
Type: Bug Report - General → Developer Task
Version: Unspecified → Master Head

comment:2 Changed 12 years ago by danielk

Milestone: 0.26 → 0.27

comment:3 Changed 12 years ago by danielk

With some debugging I've discovered that if you return -EAGAIN a number of times to libav it will mark the stream as having hit EOF. Even if you later reset the EOF flag any partially decoded data will be chucked by libav.

This means this solution is unworkable as is. However, we can still return partial reads as long as we avoid returning zero byte reads or -EAGAIN reads.

Changed 12 years ago by danielk

Attachment: 10658-v2.patch​ added

Rework which allows short reads, but still avoids ever returning 0 bytes.

comment:4 Changed 12 years ago by danielk

Description: modified (diff)
Summary: Rework AVFRingBuffer to return -EAGAIN when there is no data → Allow partial AVFRingBuffer reads

Changed 12 years ago by anonymous

Attachment: 10490-debug-start-new-rec-every-30-sec-v2.patch​ added

debugging patch

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