The print buffer can no longer be used afterwards,
but the len and size fields are still valid.
@argout ret_str if not NULL, used to return a permanent copy of the
buffer contents, or NULL if memory allocation fails;
if NULL, the buffer is discarded and freed
@return 0 for success or error code (probably AVERROR(ENOMEM))
Finalize a print buffer.
The print buffer can no longer be used afterwards, but the len and size fields are still valid.
@argout ret_str if not NULL, used to return a permanent copy of the buffer contents, or NULL if memory allocation fails; if NULL, the buffer is discarded and freed @return 0 for success or error code (probably AVERROR(ENOMEM))