linux/drivers/media/v4l2-core/v4l2-h264.c
Ezequiel Garcia d935856317 media: uapi: h264: Clean slice invariants syntax elements
The H.264 specification requires in section 7.4.3 "Slice header semantics",
that the following values shall be the same in all slice headers:

  pic_parameter_set_id
  frame_num
  field_pic_flag
  bottom_field_flag
  idr_pic_id
  pic_order_cnt_lsb
  delta_pic_order_cnt_bottom
  delta_pic_order_cnt[ 0 ]
  delta_pic_order_cnt[ 1 ]
  sp_for_switch_flag
  slice_group_change_cycle

These bitstream fields are part of the slice header, and therefore
passed redundantly on each slice. The purpose of the redundancy
is to make the codec fault-tolerant in network scenarios.

This is of course not needed to be reflected in the V4L2 controls,
given the bitstream has already been parsed by applications.
Therefore, move the redundant fields to the per-frame decode
parameters control (DECODE_PARAMS).

Field 'pic_parameter_set_id' is simply removed in this case,
because the PPS control must currently contain the active PPS.

Syntax elements dec_ref_pic_marking() and those related
to pic order count, remain invariant as well, and therefore,
the fields dec_ref_pic_marking_bit_size and pic_order_cnt_bit_size
are also common to all slices.

Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Tested-by: Jonas Karlman <jonas@kwiboo.se>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
2020-09-01 14:13:28 +02:00

269 lines
7.9 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* V4L2 H264 helpers.
*
* Copyright (C) 2019 Collabora, Ltd.
*
* Author: Boris Brezillon <boris.brezillon@collabora.com>
*/
#include <linux/module.h>
#include <linux/sort.h>
#include <media/v4l2-h264.h>
/**
* v4l2_h264_init_reflist_builder() - Initialize a P/B0/B1 reference list
* builder
*
* @b: the builder context to initialize
* @dec_params: decode parameters control
* @sps: SPS control
* @dpb: DPB to use when creating the reference list
*/
void
v4l2_h264_init_reflist_builder(struct v4l2_h264_reflist_builder *b,
const struct v4l2_ctrl_h264_decode_params *dec_params,
const struct v4l2_ctrl_h264_sps *sps,
const struct v4l2_h264_dpb_entry dpb[V4L2_H264_NUM_DPB_ENTRIES])
{
int cur_frame_num, max_frame_num;
unsigned int i;
max_frame_num = 1 << (sps->log2_max_frame_num_minus4 + 4);
cur_frame_num = dec_params->frame_num;
memset(b, 0, sizeof(*b));
if (!(dec_params->flags & V4L2_H264_DECODE_PARAM_FLAG_FIELD_PIC))
b->cur_pic_order_count = min(dec_params->bottom_field_order_cnt,
dec_params->top_field_order_cnt);
else if (dec_params->flags & V4L2_H264_DECODE_PARAM_FLAG_BOTTOM_FIELD)
b->cur_pic_order_count = dec_params->bottom_field_order_cnt;
else
b->cur_pic_order_count = dec_params->top_field_order_cnt;
for (i = 0; i < V4L2_H264_NUM_DPB_ENTRIES; i++) {
u32 pic_order_count;
if (!(dpb[i].flags & V4L2_H264_DPB_ENTRY_FLAG_ACTIVE))
continue;
b->refs[i].pic_num = dpb[i].pic_num;
if (dpb[i].flags & V4L2_H264_DPB_ENTRY_FLAG_LONG_TERM)
b->refs[i].longterm = true;
/*
* Handle frame_num wraparound as described in section
* '8.2.4.1 Decoding process for picture numbers' of the spec.
* TODO: This logic will have to be adjusted when we start
* supporting interlaced content.
*/
if (dpb[i].frame_num > cur_frame_num)
b->refs[i].frame_num = (int)dpb[i].frame_num -
max_frame_num;
else
b->refs[i].frame_num = dpb[i].frame_num;
if (dpb[i].fields == V4L2_H264_FRAME_REF)
pic_order_count = min(dpb[i].top_field_order_cnt,
dpb[i].bottom_field_order_cnt);
else if (dpb[i].fields & V4L2_H264_BOTTOM_FIELD_REF)
pic_order_count = dpb[i].bottom_field_order_cnt;
else
pic_order_count = dpb[i].top_field_order_cnt;
b->refs[i].pic_order_count = pic_order_count;
b->unordered_reflist[b->num_valid] = i;
b->num_valid++;
}
for (i = b->num_valid; i < ARRAY_SIZE(b->unordered_reflist); i++)
b->unordered_reflist[i] = i;
}
EXPORT_SYMBOL_GPL(v4l2_h264_init_reflist_builder);
static int v4l2_h264_p_ref_list_cmp(const void *ptra, const void *ptrb,
const void *data)
{
const struct v4l2_h264_reflist_builder *builder = data;
u8 idxa, idxb;
idxa = *((u8 *)ptra);
idxb = *((u8 *)ptrb);
if (WARN_ON(idxa >= V4L2_H264_NUM_DPB_ENTRIES ||
idxb >= V4L2_H264_NUM_DPB_ENTRIES))
return 1;
if (builder->refs[idxa].longterm != builder->refs[idxb].longterm) {
/* Short term pics first. */
if (!builder->refs[idxa].longterm)
return -1;
else
return 1;
}
/*
* Short term pics in descending pic num order, long term ones in
* ascending order.
*/
if (!builder->refs[idxa].longterm)
return builder->refs[idxb].frame_num <
builder->refs[idxa].frame_num ?
-1 : 1;
return builder->refs[idxa].pic_num < builder->refs[idxb].pic_num ?
-1 : 1;
}
static int v4l2_h264_b0_ref_list_cmp(const void *ptra, const void *ptrb,
const void *data)
{
const struct v4l2_h264_reflist_builder *builder = data;
s32 poca, pocb;
u8 idxa, idxb;
idxa = *((u8 *)ptra);
idxb = *((u8 *)ptrb);
if (WARN_ON(idxa >= V4L2_H264_NUM_DPB_ENTRIES ||
idxb >= V4L2_H264_NUM_DPB_ENTRIES))
return 1;
if (builder->refs[idxa].longterm != builder->refs[idxb].longterm) {
/* Short term pics first. */
if (!builder->refs[idxa].longterm)
return -1;
else
return 1;
}
/* Long term pics in ascending pic num order. */
if (builder->refs[idxa].longterm)
return builder->refs[idxa].pic_num <
builder->refs[idxb].pic_num ?
-1 : 1;
poca = builder->refs[idxa].pic_order_count;
pocb = builder->refs[idxb].pic_order_count;
/*
* Short term pics with POC < cur POC first in POC descending order
* followed by short term pics with POC > cur POC in POC ascending
* order.
*/
if ((poca < builder->cur_pic_order_count) !=
(pocb < builder->cur_pic_order_count))
return poca < pocb ? -1 : 1;
else if (poca < builder->cur_pic_order_count)
return pocb < poca ? -1 : 1;
return poca < pocb ? -1 : 1;
}
static int v4l2_h264_b1_ref_list_cmp(const void *ptra, const void *ptrb,
const void *data)
{
const struct v4l2_h264_reflist_builder *builder = data;
s32 poca, pocb;
u8 idxa, idxb;
idxa = *((u8 *)ptra);
idxb = *((u8 *)ptrb);
if (WARN_ON(idxa >= V4L2_H264_NUM_DPB_ENTRIES ||
idxb >= V4L2_H264_NUM_DPB_ENTRIES))
return 1;
if (builder->refs[idxa].longterm != builder->refs[idxb].longterm) {
/* Short term pics first. */
if (!builder->refs[idxa].longterm)
return -1;
else
return 1;
}
/* Long term pics in ascending pic num order. */
if (builder->refs[idxa].longterm)
return builder->refs[idxa].pic_num <
builder->refs[idxb].pic_num ?
-1 : 1;
poca = builder->refs[idxa].pic_order_count;
pocb = builder->refs[idxb].pic_order_count;
/*
* Short term pics with POC > cur POC first in POC ascending order
* followed by short term pics with POC < cur POC in POC descending
* order.
*/
if ((poca < builder->cur_pic_order_count) !=
(pocb < builder->cur_pic_order_count))
return pocb < poca ? -1 : 1;
else if (poca < builder->cur_pic_order_count)
return pocb < poca ? -1 : 1;
return poca < pocb ? -1 : 1;
}
/**
* v4l2_h264_build_p_ref_list() - Build the P reference list
*
* @builder: reference list builder context
* @reflist: 16-bytes array used to store the P reference list. Each entry
* is an index in the DPB
*
* This functions builds the P reference lists. This procedure is describe in
* section '8.2.4 Decoding process for reference picture lists construction'
* of the H264 spec. This function can be used by H264 decoder drivers that
* need to pass a P reference list to the hardware.
*/
void
v4l2_h264_build_p_ref_list(const struct v4l2_h264_reflist_builder *builder,
u8 *reflist)
{
memcpy(reflist, builder->unordered_reflist,
sizeof(builder->unordered_reflist[0]) * builder->num_valid);
sort_r(reflist, builder->num_valid, sizeof(*reflist),
v4l2_h264_p_ref_list_cmp, NULL, builder);
}
EXPORT_SYMBOL_GPL(v4l2_h264_build_p_ref_list);
/**
* v4l2_h264_build_b_ref_lists() - Build the B0/B1 reference lists
*
* @builder: reference list builder context
* @b0_reflist: 16-bytes array used to store the B0 reference list. Each entry
* is an index in the DPB
* @b1_reflist: 16-bytes array used to store the B1 reference list. Each entry
* is an index in the DPB
*
* This functions builds the B0/B1 reference lists. This procedure is described
* in section '8.2.4 Decoding process for reference picture lists construction'
* of the H264 spec. This function can be used by H264 decoder drivers that
* need to pass B0/B1 reference lists to the hardware.
*/
void
v4l2_h264_build_b_ref_lists(const struct v4l2_h264_reflist_builder *builder,
u8 *b0_reflist, u8 *b1_reflist)
{
memcpy(b0_reflist, builder->unordered_reflist,
sizeof(builder->unordered_reflist[0]) * builder->num_valid);
sort_r(b0_reflist, builder->num_valid, sizeof(*b0_reflist),
v4l2_h264_b0_ref_list_cmp, NULL, builder);
memcpy(b1_reflist, builder->unordered_reflist,
sizeof(builder->unordered_reflist[0]) * builder->num_valid);
sort_r(b1_reflist, builder->num_valid, sizeof(*b1_reflist),
v4l2_h264_b1_ref_list_cmp, NULL, builder);
if (builder->num_valid > 1 &&
!memcmp(b1_reflist, b0_reflist, builder->num_valid))
swap(b1_reflist[0], b1_reflist[1]);
}
EXPORT_SYMBOL_GPL(v4l2_h264_build_b_ref_lists);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("V4L2 H264 Helpers");
MODULE_AUTHOR("Boris Brezillon <boris.brezillon@collabora.com>");