[FFmpeg-devel] [PATCH V2 1/2] lavf/vc1test: fix vc1test can't probe some RCV file.

[mypopy at gmail.com]

On Sat, Oct 13, 2018 at 4:51 PM Jerome Borsboom
<jerome.borsboom at carpalis.nl> wrote:
>
> > On Sat, Oct 13, 2018 at 12:55 AM mypopy at gmail.com <mypopy at gmail.com> wrote:
> >>
> >> On Fri, Oct 12, 2018 at 10:35 PM Carl Eugen Hoyos <ceffmpeg at gmail.com>
> > wrote:
> >> >
> >> > 2018-10-12 15:41 GMT+02:00, Jun Zhao <mypopydev at gmail.com>:
> >> > > case 1:
> >> > > use the hexdump -C SMM0005.rcv get:
> >> > >                      size              skip (size - 4)
> >> > >                       |                        |
> >> > >                       V                        V
> >> > > 00000000  18 00 00 c5 05 00 00 00  4d f1 0a 11 00 e0 01 00
> >> > > 00000010  00 d0 02 00 00 0c 00 00  00 88 13 00 00 c0 65 52
> >> > >                          ^
> >> > >                        |
> >> > >                    size + 16
> >> > > case 2:
> >> > > same the command for SMM0015.rcv get:
> >> > >                     size
> >> > >                       |
> >> > >                       V
> >> > > 00000000  19 00 00 c5 04 00 00 00  41 f3 80 01 40 02 00 00
> >> > > 00000010  d0 02 00 00 0c 00 00 00  00 00 00 10 00 00 00 00
> >> > >                       ^
> >> > >                     |
> >> > >                  size + 16
> >> > >
> >> > > There are different the RCV file format for VC-1, vc1test
> >> > > just handle the case 2 now, this fix will support the case 1.
> >> >
> >> > Both with and without your patch, I get identical output from
> >> > FFmpeg's decoder for both SSM0015.rcv and SMM0005.rcv.
> >> > What exactly is your patch supposed to change?
> >> >
> >> > $ md5sum SMM0005.rcv
> >> > abd0fa5ec90d44f7b4865c6930d65ff2  SMM0005.rcv
> >> > $ md5sum SSM0015.rcv
> >> > 21a0281f83b7f2e99a048b180dd3347f  SSM0015.rcv
> >>
> >> In my test clips, I get md5 like this
> >> $ md5sum SMM0005.rcv
> >> 39eb225dbfafacea3e3737deba789530  SMM0005.rcv
> >> $ md5sum SMM0015.rcv
> >> 78e45e50079e143e69f69d677c37ac3b  SMM0015.rcv
> > RCV format have a different version, you can google the rcv1 rcv2 for VC-1.
> > (e,g:
> > http://www.ti.com/lit/ml/sprs363a/sprs363a.pdf), I think we use a different
> > RCV format for test clips SMM0005.rcv
>
> This has nothing to do with the version. Version is coded as the sixth
> bit in the initial byte, i.e. 0x85 = version 1, 0xc5 = version 2.
>
> VC-1(2006) is quite clear in Annex L that the second dword should be a
> 0x00000004. The reference decoder, however, is more lenient and gives
> more insight. The 0x00000004, and the 0x0000000c in the seventh dword,
> seem to be meant as a length indicator for the STRUCT_C and the
> STRUCT_B, respectively.
>
> This may be a leftover from older versions. I think it won't hurt to
> follow the reference decoder here and interpret these dwords as length
> indicators. The patch could be adjusted to do this for the 0x0000000c as
> well.
>
I agree with your, I think I get a older VC-1 test clip in this case.
>
> Regards,
> Jerome