[Ffmpeg-devel] [PATCH] ASF Stream bitrate GUID parsing....

[Ryan Martell]

Hi...

On Jan 4, 2007, at 6:59 PM, Michael Niedermayer wrote:

> Hi
>
> On Thu, Jan 04, 2007 at 04:45:22PM -0600, Ryan Martell wrote:
>> Hi--
>>
>> To support my native mms code, I need to parse the bitrate GUID
>> header of the ASF file if it's present.  This small patch adds that
>> information to the ASFContext.
>>
>> A couple of quick notes:
>>
>> 1) The indentation is actually correct now (the block below is
>> indented incorrectly) on the lines:
>> -       } else if (!memcmp(&g, &extended_content_header, sizeof
>> (GUID))) {
>> +        } else if (!memcmp(&g, &stream_bitrate_guid, sizeof 
>> (GUID))) {
>>
>> 2) I removed:
>>  ASFStream streams[128];     /* it's max number and it's not that
>> big */
>>> from the ASFContext, as it was unused (and big).  I replaced it with
>> a 128 uint32_t array, which seems fair.
> [...]
>> +        } else if (!memcmp(&g, &stream_bitrate_guid, sizeof 
>> (GUID))) {
>> +            uint16_t streams = get_le16(pb);
>> +            int j;
>> +
>> +#ifdef DEBUG
>> +            av_log(NULL, AV_LOG_ERROR, "stream bitrate properties 
>> \n");
>> +            av_log(NULL, AV_LOG_ERROR, "streams %d\n", streams);
>> +#endif
>> +
>> +            for(j = 0; j < streams; j++) {
>> +                uint16_t flags;
>> +                uint32_t bitrate;
>> +                int stream_id;
>> +
>> +                flags= get_le16(pb);
>> +                bitrate= get_le32(pb);
>> +                stream_id= (flags & 0x7f);
>> +#ifdef DEBUG
>> +                av_log(NULL, AV_LOG_ERROR, "flags: 0x%x stream id  
>> %d, bitrate %d\n", flags, stream_id, bitrate);
>> +#endif
>> +                asf->stream_bitrates[stream_id-1]= bitrate;
>
> the -1 causes a possible write prior to the array

stream_id of zero is invalid; attached patch ignores bitrate if the  
stream id is zero.

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Thanks!
-Ryan