[FFmpeg-devel] [PATCH] LATM Bitstream Filter & Parser

[Peter Holik]

> On Tuesday 26 May 2009 07:52:36 pm Paul Kendall wrote:
>> On Tuesday 26 May 2009 07:30:30 pm Reimar D?ffinger wrote:
>> > On Tue, May 26, 2009 at 06:51:30PM +1200, Paul Kendall wrote:
>> > > > > +    /* parser only codecs */
>> > > >
>> > > > parser-only
>> > >
>> > > Yes, the comment relates to the other patch I mentioned about separate
>> > > parser selection.
>> >
>> > You misunderstood, you need a "-" between parser and only, I think
>> > otherwise the statement does not make sense.
>>
>> Sorry, have added the dash.
>>
> Latest patch included, I also also changed the parser to that when it returns
> packets it sets the codec_id to CODEC_ID_AAC, which means that the AAC codec
> is used.

Please help me to understand:

latm_find_frame_end is called with a AVPacket read from a Stream.

What is if the size of the Packet is smaller than a frame?


+static int latm_find_frame_end(AVCodecParserContext *s1, const uint8_t *buf,
+                               int buf_size)
+{
+    LATMParseContext *s = s1->priv_data;
+    ParseContext *pc = &s->pc;
+    int pic_found, i;
+    uint32_t state;
+
+    pic_found = pc->frame_start_found;
+    state     = pc->state;
+
+    for (i = 0; !pic_found && i < buf_size; i++) {
+        state = (state<<8) | buf[i];
+        if ((state & LATM_MASK) == LATM_HEADER) {
+            pic_found = 1;
+            s->count  = i - 2;
+            break;
+        }
+    }
+
+    if (pic_found) {
+        /* EOF considered as end of frame */
+        if (buf_size == 0)
+            return 0;
+        if ((state & LATM_SIZE_MASK) + s->count + 3 <= buf_size) {

if the Packet is smaller (buf_size is the size of the Packet) then
"(state & LATM_SIZE_MASK) + s->count + 3 <= buf_size" can not be true?

+            pc->frame_start_found = 0;
+            pc->state             = -1;
+            return (state & LATM_SIZE_MASK) + s->count + 3;

thanks Peter