[FFmpeg-cvslog] r10908 - trunk/libavformat/mpeg.c

[Måns Rullgård]

Michael Niedermayer <michaelni at gmx.at> writes:

> On Sat, Nov 03, 2007 at 02:29:45PM +0000, M?ns Rullg?rd wrote:
>> michael <subversion at mplayerhq.hu> writes:
>> 
>> > Author: michael
>> > Date: Sat Nov  3 14:48:30 2007
>> > New Revision: 10908
>> >
>> > Log:
>> > fix misdetection of mp3could_not_find_codec_parameters.mp3
>> >
>> > Modified:
>> >    trunk/libavformat/mpeg.c
>> >
>> > Modified: trunk/libavformat/mpeg.c
>> > ==============================================================================
>> > --- trunk/libavformat/mpeg.c	(original)
>> > +++ trunk/libavformat/mpeg.c	Sat Nov  3 14:48:30 2007
>> > @@ -44,6 +44,26 @@ static int cdxa_probe(AVProbeData *p)
>> >          return 0;
>> >  }
>> >
>> > +static int check_pes(uint8_t *p, uint8_t *end){
>> > +    int pes1;
>> > +    int pes2=      (p[3] & 0xC0) == 0x80
>> > +                && (p[4] & 0xC0) != 0x40
>> > +                &&((p[4] & 0xC0) == 0x00 || (p[4]&0xC0)>>2 == (p[6]&0xF0));
>> > +
>> > +    for(p+=3; p<end && *p == 0xFF; p++);
>> 
>> What is the purpose of this?  MPEG PS doesn't have unspecified-length
>> sequences of 0xff bytes.
>
> mpeg1 systems spec:
> |packet() {                                  |          |          |
> | packet_start_code_prefix                   |24        |bslbf     |
> | stream_id                                  |8         |uimsbf    |
> | packet_length                              |16        |uimsbf    |
> | if (stream_id != private_stream_2) {       |          |          |
> |  while (nextbits() == '1111 1111')         |          |          |
> |   stuffing_byte                            |8         |bslbf     |
>
> is my copy of the spec wrong?

No, I simply forgot about MPEG1.

-- 
M?ns Rullg?rd
mans at mansr.com