All cbs-functions to write units share a common pattern:
1. They check whether they have a write buffer (that is used to store
the unit's data until the needed size becomes known after writing the
unit when a dedicated buffer will be allocated).
2. They use this buffer for a PutBitContext.
3. The (codec-specific) writing takes place through the PutBitContext.
4. The return value is checked. AVERROR(ENOSPC) here always indicates
that the buffer was too small and leads to a reallocation of said
buffer.
5. The final buffer will be allocated and the data copied.
This commit factors this common code out in a single function in cbs.c.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
The type of the result of a shift operation is unaffected by the type of
the right operand, so some existing code overflows with undefined behaviour
when the element length is 32. Add a helper macro to calculate the maximum
value correctly and then use it everywhere this pattern appears.
Found-by: Andreas Rheinhardt <andreas.rheinhardt@googlemail.com>
* commit 'ce5870a3a8f2b10668ee4f04c2ae0287f66f31b2':
cbs: Refcount all the things!
Some changes for bitstream API.
Merged-by: Mark Thompson <sw@jkqxz.net>
* commit '254e728d207c173a3714e6a01c9d68fcb3af8b73':
cbs: Minor comment fixes / cosmetics
Mostly already present, one small fix.
Merged-by: Mark Thompson <sw@jkqxz.net>
This makes it easier for users of the CBS API to get alloc/free right -
all subelements use the buffer API so that it's clear how to free them.
It also allows eliding some redundant copies: the packet -> fragment copy
disappears after this change if the input packet is refcounted, and more
codec-specific cases are now possible (but not included in this patch).
