H264Decoder: Handle gaps in frame_num.

content/common/gpu/media/v4l2_slice_video_decode_accelerator.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <fcntl.h>
 #include <linux/videodev2.h>
 #include <poll.h>
 #include <sys/eventfd.h>
 #include <sys/ioctl.h>
 #include <sys/mman.h>
@@ skipping 1759 matching lines @@
 void V4L2SliceVideoDecodeAccelerator::V4L2H264Accelerator::H264DPBToV4L2DPB(
     const H264DPB& dpb,
     std::vector<scoped_refptr<V4L2DecodeSurface>>* ref_surfaces) {
   memset(v4l2_decode_param_.dpb, 0, sizeof(v4l2_decode_param_.dpb));
   size_t i = 0;
   for (const auto& pic : dpb) {
     if (i >= arraysize(v4l2_decode_param_.dpb)) {
       DVLOG(1) << "Invalid DPB size";
       break;
     }
+
+    int index = VIDEO_MAX_FRAME;

[kcwu, 2015/10/02 13:06:04]

Why it is okay to set buf_idx=VIDEO_MAX_FRAME for nonexisting frame? Is is just
dummy unused value?

[Pawel Osciak, 2015/10/09 06:39:25]

VIDEO_MAX_FRAME is used to indicate an unused entry, as it's not a valid buffer
id.

+    if (!pic->nonexisting) {
+      scoped_refptr<V4L2DecodeSurface> dec_surface =
+          H264PictureToV4L2DecodeSurface(pic);
+      index = dec_surface->output_record();
+      ref_surfaces->push_back(dec_surface);
+    }
+
     struct v4l2_h264_dpb_entry& entry = v4l2_decode_param_.dpb[i++];
-    scoped_refptr<V4L2DecodeSurface> dec_surface =
-        H264PictureToV4L2DecodeSurface(pic);
-    entry.buf_index = dec_surface->output_record();
+    entry.buf_index = index;
     entry.frame_num = pic->frame_num;
     entry.pic_num = pic->pic_num;
     entry.top_field_order_cnt = pic->top_field_order_cnt;
     entry.bottom_field_order_cnt = pic->bottom_field_order_cnt;
     entry.flags = (pic->ref ? V4L2_H264_DPB_ENTRY_FLAG_ACTIVE : 0) |
                   (pic->long_term ? V4L2_H264_DPB_ENTRY_FLAG_LONG_TERM : 0);
-
-    ref_surfaces->push_back(dec_surface);
   }
 }
 
 bool V4L2SliceVideoDecodeAccelerator::V4L2H264Accelerator::SubmitFrameMetadata(
     const media::H264SPS* sps,
     const media::H264PPS* pps,
     const H264DPB& dpb,
     const H264Picture::Vector& ref_pic_listp0,
     const H264Picture::Vector& ref_pic_listb0,
     const H264Picture::Vector& ref_pic_listb1,
@@ skipping 731 matching lines @@
   if (!device)
     return SupportedProfiles();
 
   const uint32_t supported_formats[] = {
       V4L2_PIX_FMT_H264_SLICE, V4L2_PIX_FMT_VP8_FRAME};
   return device->GetSupportedDecodeProfiles(arraysize(supported_formats),
                                             supported_formats);
 }
 
 }  // namespace content