Libav
dxva2_vc1.c
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1 /*
2  * DXVA2 WMV3/VC-1 HW acceleration.
3  *
4  * copyright (c) 2010 Laurent Aimar
5  *
6  * This file is part of Libav.
7  *
8  * Libav is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * Libav is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with Libav; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 #include "mpegutils.h"
24 #include "vc1.h"
25 #include "vc1data.h"
26 
27 // The headers above may include w32threads.h, which uses the original
28 // _WIN32_WINNT define, while dxva2_internal.h redefines it to target a
29 // potentially newer version.
30 #include "dxva2_internal.h"
31 
32 struct dxva2_picture_context {
33  DXVA_PictureParameters pp;
34  DXVA_SliceInfo si;
35 
36  const uint8_t *bitstream;
37  unsigned bitstream_size;
38 };
39 
41  AVDXVAContext *ctx, const VC1Context *v,
42  DXVA_PictureParameters *pp)
43 {
44  const MpegEncContext *s = &v->s;
45  const Picture *current_picture = s->current_picture_ptr;
46 
47  memset(pp, 0, sizeof(*pp));
48  pp->wDecodedPictureIndex =
49  pp->wDeblockedPictureIndex = ff_dxva2_get_surface_index(avctx, ctx, current_picture->f);
50  if (s->pict_type != AV_PICTURE_TYPE_I && !v->bi_type)
51  pp->wForwardRefPictureIndex = ff_dxva2_get_surface_index(avctx, ctx, s->last_picture.f);
52  else
53  pp->wForwardRefPictureIndex = 0xffff;
54  if (s->pict_type == AV_PICTURE_TYPE_B && !v->bi_type)
55  pp->wBackwardRefPictureIndex = ff_dxva2_get_surface_index(avctx, ctx, s->next_picture.f);
56  else
57  pp->wBackwardRefPictureIndex = 0xffff;
58  if (v->profile == PROFILE_ADVANCED) {
59  /* It is the cropped width/height -1 of the frame */
60  pp->wPicWidthInMBminus1 = avctx->width - 1;
61  pp->wPicHeightInMBminus1= avctx->height - 1;
62  } else {
63  /* It is the coded width/height in macroblock -1 of the frame */
64  pp->wPicWidthInMBminus1 = s->mb_width - 1;
65  pp->wPicHeightInMBminus1= s->mb_height - 1;
66  }
67  pp->bMacroblockWidthMinus1 = 15;
68  pp->bMacroblockHeightMinus1 = 15;
69  pp->bBlockWidthMinus1 = 7;
70  pp->bBlockHeightMinus1 = 7;
71  pp->bBPPminus1 = 7;
73  pp->bPicStructure |= 0x01;
75  pp->bPicStructure |= 0x02;
76  pp->bSecondField = v->interlace && v->fcm != ILACE_FIELD && !s->first_field;
77  pp->bPicIntra = s->pict_type == AV_PICTURE_TYPE_I || v->bi_type;
78  pp->bPicBackwardPrediction = s->pict_type == AV_PICTURE_TYPE_B && !v->bi_type;
79  pp->bBidirectionalAveragingMode = (1 << 7) |
80  ((DXVA_CONTEXT_CFG_INTRARESID(avctx, ctx) != 0) << 6) |
81  ((DXVA_CONTEXT_CFG_RESIDACCEL(avctx, ctx) != 0) << 5) |
82  ((v->lumscale != 32 || v->lumshift != 0) << 4) |
83  ((v->profile == PROFILE_ADVANCED) << 3);
84  pp->bMVprecisionAndChromaRelation = ((v->mv_mode == MV_PMODE_1MV_HPEL_BILIN) << 3) |
85  (1 << 2) |
86  (0 << 1) |
87  (!s->quarter_sample );
88  pp->bChromaFormat = v->chromaformat;
89  DXVA_CONTEXT_REPORT_ID(avctx, ctx)++;
90  if (DXVA_CONTEXT_REPORT_ID(avctx, ctx) >= (1 << 16))
91  DXVA_CONTEXT_REPORT_ID(avctx, ctx) = 1;
92  pp->bPicScanFixed = DXVA_CONTEXT_REPORT_ID(avctx, ctx) >> 8;
93  pp->bPicScanMethod = DXVA_CONTEXT_REPORT_ID(avctx, ctx) & 0xff;
94  pp->bPicReadbackRequests = 0;
95  pp->bRcontrol = v->rnd;
96  pp->bPicSpatialResid8 = (v->panscanflag << 7) |
97  (v->refdist_flag << 6) |
98  (s->loop_filter << 5) |
99  (v->fastuvmc << 4) |
100  (v->extended_mv << 3) |
101  (v->dquant << 1) |
102  (v->vstransform );
103  pp->bPicOverflowBlocks = (v->quantizer_mode << 6) |
104  (v->multires << 5) |
105  (v->resync_marker << 4) |
106  (v->rangered << 3) |
107  (s->max_b_frames );
108  pp->bPicExtrapolation = (!v->interlace || v->fcm == PROGRESSIVE) ? 1 : 2;
109  pp->bPicDeblocked = ((!pp->bPicBackwardPrediction && v->overlap) << 6) |
110  ((v->profile != PROFILE_ADVANCED && v->rangeredfrm) << 5) |
111  (s->loop_filter << 1);
112  pp->bPicDeblockConfined = (v->postprocflag << 7) |
113  (v->broadcast << 6) |
114  (v->interlace << 5) |
115  (v->tfcntrflag << 4) |
116  (v->finterpflag << 3) |
117  ((s->pict_type != AV_PICTURE_TYPE_B) << 2) |
118  (v->psf << 1) |
119  (v->extended_dmv );
120  if (s->pict_type != AV_PICTURE_TYPE_I)
121  pp->bPic4MVallowed = v->mv_mode == MV_PMODE_MIXED_MV ||
124  if (v->profile == PROFILE_ADVANCED)
125  pp->bPicOBMC = (v->range_mapy_flag << 7) |
126  (v->range_mapy << 4) |
127  (v->range_mapuv_flag << 3) |
128  (v->range_mapuv );
129  pp->bPicBinPB = 0;
130  pp->bMV_RPS = 0;
131  pp->bReservedBits = 0;
132  if (s->picture_structure == PICT_FRAME) {
133  pp->wBitstreamFcodes = v->lumscale;
134  pp->wBitstreamPCEelements = v->lumshift;
135  } else {
136  /* Syntax: (top_field_param << 8) | bottom_field_param */
137  pp->wBitstreamFcodes = (v->lumscale << 8) | v->lumscale;
138  pp->wBitstreamPCEelements = (v->lumshift << 8) | v->lumshift;
139  }
140  pp->bBitstreamConcealmentNeed = 0;
141  pp->bBitstreamConcealmentMethod = 0;
142 }
143 
144 static void fill_slice(AVCodecContext *avctx, DXVA_SliceInfo *slice,
145  unsigned position, unsigned size)
146 {
147  const VC1Context *v = avctx->priv_data;
148  const MpegEncContext *s = &v->s;
149 
150  memset(slice, 0, sizeof(*slice));
151  slice->wHorizontalPosition = 0;
152  slice->wVerticalPosition = s->mb_y;
153  slice->dwSliceBitsInBuffer = 8 * size;
154  slice->dwSliceDataLocation = position;
155  slice->bStartCodeBitOffset = 0;
156  slice->bReservedBits = 0;
157  slice->wMBbitOffset = get_bits_count(&s->gb);
158  slice->wNumberMBsInSlice = s->mb_width * s->mb_height; /* XXX We assume 1 slice */
159  slice->wQuantizerScaleCode = v->pq;
160  slice->wBadSliceChopping = 0;
161 }
162 
166 {
167  const VC1Context *v = avctx->priv_data;
169  const MpegEncContext *s = &v->s;
171 
172  DXVA_SliceInfo *slice = &ctx_pic->si;
173 
174  static const uint8_t start_code[] = { 0, 0, 1, 0x0d };
175  const unsigned start_code_size = avctx->codec_id == AV_CODEC_ID_VC1 ? sizeof(start_code) : 0;
176  const unsigned slice_size = slice->dwSliceBitsInBuffer / 8;
177  const unsigned padding = 128 - ((start_code_size + slice_size) & 127);
178  const unsigned data_size = start_code_size + slice_size + padding;
179 
180  void *dxva_data_ptr;
181  uint8_t *dxva_data;
182  unsigned dxva_size;
183  int result;
184  unsigned type;
185 
186 #if CONFIG_D3D11VA
187  if (avctx->pix_fmt == AV_PIX_FMT_D3D11VA_VLD) {
188  type = D3D11_VIDEO_DECODER_BUFFER_BITSTREAM;
189  if (FAILED(ID3D11VideoContext_GetDecoderBuffer(D3D11VA_CONTEXT(ctx)->video_context,
190  D3D11VA_CONTEXT(ctx)->decoder,
191  type,
192  &dxva_size, &dxva_data_ptr)))
193  return -1;
194  }
195 #endif
196 #if CONFIG_DXVA2
197  if (avctx->pix_fmt == AV_PIX_FMT_DXVA2_VLD) {
198  type = DXVA2_BitStreamDateBufferType;
199  if (FAILED(IDirectXVideoDecoder_GetBuffer(DXVA2_CONTEXT(ctx)->decoder,
200  type,
201  &dxva_data_ptr, &dxva_size)))
202  return -1;
203  }
204 #endif
205 
206  dxva_data = dxva_data_ptr;
207  result = data_size <= dxva_size ? 0 : -1;
208  if (!result) {
209  if (start_code_size > 0)
210  memcpy(dxva_data, start_code, start_code_size);
211  memcpy(dxva_data + start_code_size,
212  ctx_pic->bitstream + slice->dwSliceDataLocation, slice_size);
213  if (padding > 0)
214  memset(dxva_data + start_code_size + slice_size, 0, padding);
215  slice->dwSliceBitsInBuffer = 8 * data_size;
216  }
217 #if CONFIG_D3D11VA
218  if (avctx->pix_fmt == AV_PIX_FMT_D3D11VA_VLD)
219  if (FAILED(ID3D11VideoContext_ReleaseDecoderBuffer(D3D11VA_CONTEXT(ctx)->video_context, D3D11VA_CONTEXT(ctx)->decoder, type)))
220  return -1;
221 #endif
222 #if CONFIG_DXVA2
223  if (avctx->pix_fmt == AV_PIX_FMT_DXVA2_VLD)
224  if (FAILED(IDirectXVideoDecoder_ReleaseBuffer(DXVA2_CONTEXT(ctx)->decoder, type)))
225  return -1;
226 #endif
227  if (result)
228  return result;
229 
230 #if CONFIG_D3D11VA
231  if (avctx->pix_fmt == AV_PIX_FMT_D3D11VA_VLD) {
232  D3D11_VIDEO_DECODER_BUFFER_DESC *dsc11 = bs;
233  memset(dsc11, 0, sizeof(*dsc11));
234  dsc11->BufferType = type;
235  dsc11->DataSize = data_size;
236  dsc11->NumMBsInBuffer = s->mb_width * s->mb_height;
237 
238  type = D3D11_VIDEO_DECODER_BUFFER_SLICE_CONTROL;
239  }
240 #endif
241 #if CONFIG_DXVA2
242  if (avctx->pix_fmt == AV_PIX_FMT_DXVA2_VLD) {
243  DXVA2_DecodeBufferDesc *dsc2 = bs;
244  memset(dsc2, 0, sizeof(*dsc2));
245  dsc2->CompressedBufferType = type;
246  dsc2->DataSize = data_size;
247  dsc2->NumMBsInBuffer = s->mb_width * s->mb_height;
248 
249  type = DXVA2_SliceControlBufferType;
250  }
251 #endif
252  assert((data_size & 127) == 0);
253 
254  return ff_dxva2_commit_buffer(avctx, ctx, sc,
255  type,
256  slice, sizeof(*slice), s->mb_width * s->mb_height);
257 }
258 
260  av_unused const uint8_t *buffer,
261  av_unused uint32_t size)
262 {
263  const VC1Context *v = avctx->priv_data;
266 
267  if (DXVA_CONTEXT_DECODER(avctx, ctx) == NULL ||
268  DXVA_CONTEXT_CFG(avctx, ctx) == NULL ||
269  DXVA_CONTEXT_COUNT(avctx, ctx) <= 0)
270  return -1;
271  assert(ctx_pic);
272 
273  fill_picture_parameters(avctx, ctx, v, &ctx_pic->pp);
274 
275  ctx_pic->bitstream_size = 0;
276  ctx_pic->bitstream = NULL;
277  return 0;
278 }
279 
281  const uint8_t *buffer,
282  uint32_t size)
283 {
284  const VC1Context *v = avctx->priv_data;
285  const Picture *current_picture = v->s.current_picture_ptr;
286  struct dxva2_picture_context *ctx_pic = current_picture->hwaccel_picture_private;
287 
288  if (ctx_pic->bitstream_size > 0)
289  return -1;
290 
291  if (avctx->codec_id == AV_CODEC_ID_VC1 &&
292  size >= 4 && IS_MARKER(AV_RB32(buffer))) {
293  buffer += 4;
294  size -= 4;
295  }
296 
297  ctx_pic->bitstream_size = size;
298  ctx_pic->bitstream = buffer;
299 
300  fill_slice(avctx, &ctx_pic->si, 0, size);
301  return 0;
302 }
303 
305 {
306  VC1Context *v = avctx->priv_data;
308  int ret;
309 
310  if (ctx_pic->bitstream_size <= 0)
311  return -1;
312 
314  &ctx_pic->pp, sizeof(ctx_pic->pp),
315  NULL, 0,
317  if (!ret)
318  ff_mpeg_draw_horiz_band(&v->s, 0, avctx->height);
319  return ret;
320 }
321 
322 #if CONFIG_WMV3_DXVA2_HWACCEL
323 AVHWAccel ff_wmv3_dxva2_hwaccel = {
324  .name = "wmv3_dxva2",
325  .type = AVMEDIA_TYPE_VIDEO,
326  .id = AV_CODEC_ID_WMV3,
327  .pix_fmt = AV_PIX_FMT_DXVA2_VLD,
328  .start_frame = dxva2_vc1_start_frame,
329  .decode_slice = dxva2_vc1_decode_slice,
330  .end_frame = dxva2_vc1_end_frame,
331  .frame_priv_data_size = sizeof(struct dxva2_picture_context),
332 };
333 #endif
334 
335 #if CONFIG_VC1_DXVA2_HWACCEL
336 AVHWAccel ff_vc1_dxva2_hwaccel = {
337  .name = "vc1_dxva2",
338  .type = AVMEDIA_TYPE_VIDEO,
339  .id = AV_CODEC_ID_VC1,
340  .pix_fmt = AV_PIX_FMT_DXVA2_VLD,
341  .start_frame = dxva2_vc1_start_frame,
342  .decode_slice = dxva2_vc1_decode_slice,
343  .end_frame = dxva2_vc1_end_frame,
344  .frame_priv_data_size = sizeof(struct dxva2_picture_context),
345 };
346 #endif
347 
348 #if CONFIG_WMV3_D3D11VA_HWACCEL
349 AVHWAccel ff_wmv3_d3d11va_hwaccel = {
350  .name = "wmv3_d3d11va",
351  .type = AVMEDIA_TYPE_VIDEO,
352  .id = AV_CODEC_ID_WMV3,
353  .pix_fmt = AV_PIX_FMT_D3D11VA_VLD,
354  .start_frame = dxva2_vc1_start_frame,
355  .decode_slice = dxva2_vc1_decode_slice,
356  .end_frame = dxva2_vc1_end_frame,
357  .frame_priv_data_size = sizeof(struct dxva2_picture_context),
358 };
359 #endif
360 
361 #if CONFIG_VC1_D3D11VA_HWACCEL
362 AVHWAccel ff_vc1_d3d11va_hwaccel = {
363  .name = "vc1_d3d11va",
364  .type = AVMEDIA_TYPE_VIDEO,
365  .id = AV_CODEC_ID_VC1,
366  .pix_fmt = AV_PIX_FMT_D3D11VA_VLD,
367  .start_frame = dxva2_vc1_start_frame,
368  .decode_slice = dxva2_vc1_decode_slice,
369  .end_frame = dxva2_vc1_end_frame,
370  .frame_priv_data_size = sizeof(struct dxva2_picture_context),
371 };
372 #endif
in the bitstream is reported as 00b
Definition: vc1.h:149
The VC1 Context.
Definition: vc1.h:158
int size
DXVA_SliceInfo si
Definition: dxva2_vc1.c:34
int extended_mv
Ext MV in P/B (not in Simple)
Definition: vc1.h:207
int broadcast
TFF/RFF present.
Definition: vc1.h:185
uint8_t rangeredfrm
Frame decoding info for S/M profiles only.
Definition: vc1.h:286
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:1621
DXVA_PicParams_H264 pp
Definition: dxva2_h264.c:34
int fastuvmc
Rounding of qpel vector to hpel ? (not in Simple)
Definition: vc1.h:206
DXVA_SliceInfo slice[MAX_SLICES]
Definition: dxva2_mpeg2.c:37
void ff_mpeg_draw_horiz_band(MpegEncContext *s, int y, int h)
Definition: mpegvideo.c:1737
VC-1 tables.
int bi_type
Definition: vc1.h:365
static char buffer[20]
Definition: seek.c:32
uint8_t
void * hwaccel_context
Hardware accelerator context.
Definition: avcodec.h:2708
int panscanflag
NUMPANSCANWIN, TOPLEFT{X,Y}, BOTRIGHT{X,Y} present.
Definition: vc1.h:188
#define AV_RB32
Definition: intreadwrite.h:130
int interlace
Progressive/interlaced (RPTFTM syntax element)
Definition: vc1.h:186
int ff_dxva2_common_end_frame(AVCodecContext *avctx, AVFrame *frame, const void *pp, unsigned pp_size, const void *qm, unsigned qm_size, int(*commit_bs_si)(AVCodecContext *, DECODER_BUFFER_DESC *bs, DECODER_BUFFER_DESC *slice))
Definition: dxva2.c:125
int profile
Sequence header data for all Profiles TODO: choose between ints, uint8_ts and monobit flags...
Definition: vc1.h:203
#define PICT_BOTTOM_FIELD
Definition: mpegutils.h:38
static int get_bits_count(const GetBitContext *s)
Definition: get_bits.h:182
int refdist_flag
REFDIST syntax element present in II, IP, PI or PP field picture headers.
Definition: vc1.h:189
int mb_height
number of MBs horizontally & vertically
Definition: mpegvideo.h:124
static int dxva2_vc1_decode_slice(AVCodecContext *avctx, const uint8_t *buffer, uint32_t size)
Definition: dxva2_vc1.c:280
int psf
Progressive Segmented Frame.
Definition: vc1.h:196
int overlap
overlapped transforms in use
Definition: vc1.h:210
in the bitstream is reported as 11b
Definition: vc1.h:151
#define IS_MARKER(state)
Definition: dca_parser.c:45
#define PICT_TOP_FIELD
Definition: mpegutils.h:37
int quarter_sample
1->qpel, 0->half pel ME/MC
Definition: mpegvideo.h:386
GetBitContext gb
Definition: mpegvideo.h:431
int resync_marker
could this stream contain resync markers
Definition: vc1.h:380
int postprocflag
Per-frame processing suggestion flag present.
Definition: vc1.h:184
static void fill_picture_parameters(AVCodecContext *avctx, AVDXVAContext *ctx, const VC1Context *v, DXVA_PictureParameters *pp)
Definition: dxva2_vc1.c:40
const char * name
Name of the hardware accelerated codec.
Definition: avcodec.h:3244
int tfcntrflag
TFCNTR present.
Definition: vc1.h:187
static const chunk_decoder decoder[8]
Definition: dfa.c:322
int width
picture width / height.
Definition: avcodec.h:1580
uint8_t mv_mode
Frame decoding info for all profiles.
Definition: vc1.h:217
Picture * current_picture_ptr
pointer to the current picture
Definition: mpegvideo.h:179
Picture.
Definition: mpegpicture.h:45
void * hwaccel_picture_private
Hardware accelerator private data.
Definition: mpegpicture.h:74
AVFormatContext * ctx
Definition: movenc.c:48
uint8_t lumscale
Luma compensation parameters.
Definition: vc1.h:253
uint8_t range_mapuv_flag
Definition: vc1.h:313
unsigned bitstream_size
Definition: dxva2_h264.c:40
static void fill_slice(AVCodecContext *avctx, DXVA_SliceInfo *slice, unsigned position, unsigned size)
Definition: dxva2_vc1.c:144
int first_field
is 1 for the first field of a field picture 0 otherwise
Definition: mpegvideo.h:465
int rangered
RANGEREDFRM (range reduction) syntax element present at frame level.
Definition: vc1.h:174
int finterpflag
INTERPFRM present.
Definition: vc1.h:212
NULL
Definition: eval.c:55
int chromaformat
2 bits, 2=4:2:0, only defined
Definition: vc1.h:183
enum AVCodecID codec_id
Definition: avcodec.h:1426
unsigned ff_dxva2_get_surface_index(const AVCodecContext *avctx, const AVDXVAContext *ctx, const AVFrame *frame)
Definition: dxva2.c:37
int multires
frame-level RESPIC syntax element present
Definition: vc1.h:171
main external API structure.
Definition: avcodec.h:1409
uint8_t range_mapy
Definition: vc1.h:314
int ff_dxva2_commit_buffer(AVCodecContext *avctx, AVDXVAContext *ctx, DECODER_BUFFER_DESC *dsc, unsigned type, const void *data, unsigned size, unsigned mb_count)
Definition: dxva2.c:52
int extended_dmv
Additional extended dmv range at P/B-frame-level.
Definition: vc1.h:190
struct AVFrame * f
Definition: mpegpicture.h:46
static int commit_bitstream_and_slice_buffer(AVCodecContext *avctx, DECODER_BUFFER_DESC *bs, DECODER_BUFFER_DESC *sc)
Definition: dxva2_vc1.c:163
void DECODER_BUFFER_DESC
int quantizer_mode
2 bits, quantizer mode used for sequence, see QUANT_*
Definition: vc1.h:211
HW decoding through DXVA2, Picture.data[3] contains a LPDIRECT3DSURFACE9 pointer. ...
Definition: pixfmt.h:137
int max_b_frames
max number of B-frames for encoding
Definition: mpegvideo.h:110
int pict_type
AV_PICTURE_TYPE_I, AV_PICTURE_TYPE_P, AV_PICTURE_TYPE_B, ...
Definition: mpegvideo.h:206
int vstransform
variable-size [48]x[48] transform type + info
Definition: vc1.h:209
uint8_t range_mapuv
Definition: vc1.h:315
MpegEncContext s
Definition: vc1.h:159
MpegEncContext.
Definition: mpegvideo.h:76
static int dxva2_vc1_start_frame(AVCodecContext *avctx, av_unused const uint8_t *buffer, av_unused uint32_t size)
Definition: dxva2_vc1.c:259
const uint8_t * bitstream
Definition: dxva2_h264.c:39
uint8_t pq
Definition: vc1.h:222
enum FrameCodingMode fcm
Frame decoding info for Advanced profile.
Definition: vc1.h:292
Picture last_picture
copy of the previous picture structure.
Definition: mpegvideo.h:157
uint8_t lumshift
Definition: vc1.h:254
Bi-dir predicted.
Definition: avutil.h:262
void * priv_data
Definition: avcodec.h:1451
#define PICT_FRAME
Definition: mpegutils.h:39
int picture_structure
Definition: mpegvideo.h:443
int rnd
rounding control
Definition: vc1.h:282
static int dxva2_vc1_end_frame(AVCodecContext *avctx)
Definition: dxva2_vc1.c:304
Picture next_picture
copy of the next picture structure.
Definition: mpegvideo.h:163
uint8_t range_mapy_flag
Definition: vc1.h:312
HW decoding through Direct3D11, Picture.data[3] contains a ID3D11VideoDecoderOutputView pointer...
Definition: pixfmt.h:222
int dquant
How qscale varies with MBs, 2 bits (not in Simple)
Definition: vc1.h:208
uint8_t mv_mode2
Secondary MV coding mode (B-frames)
Definition: vc1.h:218
#define av_unused
Definition: attributes.h:86