[Libva] mpeg4 decoding

[Varga, Michael]

Hi Gwenole,

I double checked vop_time_increment and its not strictly needed, setting this value to 0 works but if you'll add it I'll use anyway. My patch is below. I declared modulo_time_base with 4 bits, the MPEG4 spec does not specify an upper bound for the size of this variable. If you think this is too big I can reduce it. Also, is there anything you think I should know about your process for submitting patches? Thanks! :)


>From 44aeb5d81789c42404d6a2398ef06699aabc6d73 Mon Sep 17 00:00:00 2001
From: Michael Varga <Michael.Varga at amd.com>
Date: Fri, 31 Oct 2014 08:58:34 -0500
Subject: [PATCH] va: added two variables to VAPictureParameterBufferMPEG4

Added modulo_time_base and vop_time_increment so the VOP header may be
reconstructed if it has been truncated.

Signed-off-by: Michael Varga <Michael.Varga at amd.com>
---
 va/va.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/va/va.h b/va/va.h
index 01694a9..c21770c 100644
--- a/va/va.h
+++ b/va/va.h
@@ -1312,12 +1312,14 @@ typedef struct _VAPictureParameterBufferMPEG4
             unsigned int intra_dc_vlc_thr              : 3; 
             unsigned int top_field_first               : 1; 
             unsigned int alternate_vertical_scan_flag  : 1; 
+            unsigned int modulo_time_base              : 4;
         } bits;
         unsigned int value;
     } vop_fields;
     unsigned char vop_fcode_forward;
     unsigned char vop_fcode_backward;
     unsigned short vop_time_increment_resolution;
+    unsigned short vop_time_increment;
     /* short header related */
     unsigned char num_gobs_in_vop;
     unsigned char num_macroblocks_in_gob;
-- 
1.9.1



________________________________________
From: Gwenole Beauchesne [gb.devel at gmail.com]
Sent: Friday, October 31, 2014 1:54 AM
To: Varga, Michael
Cc: libva at lists.freedesktop.org
Subject: Re: [Libva] mpeg4 decoding

Hi Michael,

2014-10-30 16:37 GMT+01:00 Varga, Michael <Michael.Varga at amd.com>:
> Hello,
>
> I am working to implement VAAPI mpeg4 decoding in MESA. I am currently
> trying to remedy a scenario where the VideoObjectPlane() (VOP) header is
> truncated from the input slice data. If the VOP header is truncated I need
> to regenerate it and add it to the front of the bitstream. It would appear
> one variable is missing from "VAPictureParameterBufferMPEG4" to generate the
> VOP header, the variable "modulo_time_base". I have seen a hacky method for
> generating this variable but I think it would be better to pass it in using
> the struct "VAPictureParameterBufferMPEG4". Would you be willing to add this
> variable?

Could you please review all the new fields you need and validate on
the changed structs? i.e. I'd prefer adding more fields at once,
rather than going piecemal. :)

In particular, I believe you would also need the actual
vop_time_increment bits, right?

Thanks,
--
Gwenole Beauchesne
Intel Corporation SAS / 2 rue de Paris, 92196 Meudon Cedex, France
Registration Number (RCS): Nanterre B 302 456 199