[FFmpeg-cvslog] r24280 - trunk/libavformat/aviobuf.c
Reinhard Tartler
siretart
Mon Jul 19 22:00:06 CEST 2010
On Sat, Jul 17, 2010 at 21:17:01 (CEST), Michael Niedermayer wrote:
> On Sat, Jul 17, 2010 at 07:26:30AM +0200, mstorsjo wrote:
>> Author: mstorsjo
>> Date: Sat Jul 17 07:26:30 2010
>> New Revision: 24280
>>
>> Log:
>> aviobuf: Do short seeks forward by reading and skipping data instead of a proper seek
>>
>> This improves performance on e.g. seekable http.
>
> This one is a candidate for backporting to 0.5/0.6 if it applies
thanks for the hint, applied to 0.6 cleanly.
For 0.5, this hunk did not apply that cleanly, here is the resulting
diff:
Index: libavformat/aviobuf.c
===================================================================
--- libavformat/aviobuf.c (Revision 24335)
+++ libavformat/aviobuf.c (Arbeitskopie)
@@ -27,6 +27,13 @@
#define IO_BUFFER_SIZE 32768
+/**
+ * Do seeks within this distance ahead of the current buffer by skipping
+ * data instead of calling the protocol seek function, for seekable
+ * protocols.
+ */
+#define SHORT_SEEK_THRESHOLD 4096
+
static void fill_buffer(ByteIOContext *s);
int init_put_byte(ByteIOContext *s,
@@ -151,8 +158,10 @@
offset1 >= 0 && offset1 < (s->buf_end - s->buffer)) {
/* can do the seek inside the buffer */
s->buf_ptr = s->buffer + offset1;
- } else if(s->is_streamed && !s->write_flag &&
- offset1 >= 0 && offset1 < (s->buf_end - s->buffer) + (1<<16)){
+ } else if ((s->is_streamed ||
+ offset1 <= s->buf_end + SHORT_SEEK_THRESHOLD - s->buffer) &&
+ !s->write_flag && offset1 >= 0 &&
+ (whence != SEEK_END || force)) {
while(s->pos < offset && !s->eof_reached)
fill_buffer(s);
if (s->eof_reached)
I'd feel more comfortable if someone could take a look if the old
condition "offset1 < (s->buf_end - s->buffer) + (1<<16)" can be really
replaced with "offset1 <= s->buf_end + SHORT_SEEK_THRESHOLD - s->buffer)"
I guess yes, but another eyeball would make me feel more comfortable.
--
Gruesse/greetings,
Reinhard Tartler, KeyID 945348A4
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