blob: 0ab2fcbee1b93b614f4366b21043dbe1323e245f [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2019 Pengutronix, Michael Tretter <kernel@pengutronix.de>
*
* Convert NAL units between raw byte sequence payloads (RBSP) and C structs
*
* The conversion is defined in "ITU-T Rec. H.264 (04/2017) Advanced video
* coding for generic audiovisual services". Decoder drivers may use the
* parser to parse RBSP from encoded streams and configure the hardware, if
* the hardware is not able to parse RBSP itself. Encoder drivers may use the
* generator to generate the RBSP for SPS/PPS nal units and add them to the
* encoded stream if the hardware does not generate the units.
*/
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/v4l2-controls.h>
#include <linux/device.h>
#include <linux/export.h>
#include <linux/log2.h>
#include "nal-h264.h"
#include "nal-rbsp.h"
/*
* See Rec. ITU-T H.264 (04/2017) Table 7-1 - NAL unit type codes, syntax
* element categories, and NAL unit type classes
*/
enum nal_unit_type {
SEQUENCE_PARAMETER_SET = 7,
PICTURE_PARAMETER_SET = 8,
FILLER_DATA = 12,
};
/**
* nal_h264_profile_from_v4l2() - Get profile_idc for v4l2 h264 profile
* @profile: the profile as &enum v4l2_mpeg_video_h264_profile
*
* Convert the &enum v4l2_mpeg_video_h264_profile to profile_idc as specified
* in Rec. ITU-T H.264 (04/2017) A.2.
*
* Return: the profile_idc for the passed level
*/
int nal_h264_profile_from_v4l2(enum v4l2_mpeg_video_h264_profile profile)
{
switch (profile) {
case V4L2_MPEG_VIDEO_H264_PROFILE_BASELINE:
return 66;
case V4L2_MPEG_VIDEO_H264_PROFILE_MAIN:
return 77;
case V4L2_MPEG_VIDEO_H264_PROFILE_EXTENDED:
return 88;
case V4L2_MPEG_VIDEO_H264_PROFILE_HIGH:
return 100;
default:
return -EINVAL;
}
}
/**
* nal_h264_level_from_v4l2() - Get level_idc for v4l2 h264 level
* @level: the level as &enum v4l2_mpeg_video_h264_level
*
* Convert the &enum v4l2_mpeg_video_h264_level to level_idc as specified in
* Rec. ITU-T H.264 (04/2017) A.3.2.
*
* Return: the level_idc for the passed level
*/
int nal_h264_level_from_v4l2(enum v4l2_mpeg_video_h264_level level)
{
switch (level) {
case V4L2_MPEG_VIDEO_H264_LEVEL_1_0:
return 10;
case V4L2_MPEG_VIDEO_H264_LEVEL_1B:
return 9;
case V4L2_MPEG_VIDEO_H264_LEVEL_1_1:
return 11;
case V4L2_MPEG_VIDEO_H264_LEVEL_1_2:
return 12;
case V4L2_MPEG_VIDEO_H264_LEVEL_1_3:
return 13;
case V4L2_MPEG_VIDEO_H264_LEVEL_2_0:
return 20;
case V4L2_MPEG_VIDEO_H264_LEVEL_2_1:
return 21;
case V4L2_MPEG_VIDEO_H264_LEVEL_2_2:
return 22;
case V4L2_MPEG_VIDEO_H264_LEVEL_3_0:
return 30;
case V4L2_MPEG_VIDEO_H264_LEVEL_3_1:
return 31;
case V4L2_MPEG_VIDEO_H264_LEVEL_3_2:
return 32;
case V4L2_MPEG_VIDEO_H264_LEVEL_4_0:
return 40;
case V4L2_MPEG_VIDEO_H264_LEVEL_4_1:
return 41;
case V4L2_MPEG_VIDEO_H264_LEVEL_4_2:
return 42;
case V4L2_MPEG_VIDEO_H264_LEVEL_5_0:
return 50;
case V4L2_MPEG_VIDEO_H264_LEVEL_5_1:
return 51;
default:
return -EINVAL;
}
}
static void nal_h264_write_start_code_prefix(struct rbsp *rbsp)
{
u8 *p = rbsp->data + DIV_ROUND_UP(rbsp->pos, 8);
int i = 4;
if (DIV_ROUND_UP(rbsp->pos, 8) + i > rbsp->size) {
rbsp->error = -EINVAL;
return;
}
p[0] = 0x00;
p[1] = 0x00;
p[2] = 0x00;
p[3] = 0x01;
rbsp->pos += i * 8;
}
static void nal_h264_read_start_code_prefix(struct rbsp *rbsp)
{
u8 *p = rbsp->data + DIV_ROUND_UP(rbsp->pos, 8);
int i = 4;
if (DIV_ROUND_UP(rbsp->pos, 8) + i > rbsp->size) {
rbsp->error = -EINVAL;
return;
}
if (p[0] != 0x00 || p[1] != 0x00 || p[2] != 0x00 || p[3] != 0x01) {
rbsp->error = -EINVAL;
return;
}
rbsp->pos += i * 8;
}
static void nal_h264_write_filler_data(struct rbsp *rbsp)
{
u8 *p = rbsp->data + DIV_ROUND_UP(rbsp->pos, 8);
int i;
/* Keep 1 byte extra for terminating the NAL unit */
i = rbsp->size - DIV_ROUND_UP(rbsp->pos, 8) - 1;
memset(p, 0xff, i);
rbsp->pos += i * 8;
}
static void nal_h264_read_filler_data(struct rbsp *rbsp)
{
u8 *p = rbsp->data + DIV_ROUND_UP(rbsp->pos, 8);
while (*p == 0xff) {
if (DIV_ROUND_UP(rbsp->pos, 8) > rbsp->size) {
rbsp->error = -EINVAL;
return;
}
p++;
rbsp->pos += 8;
}
}
static void nal_h264_rbsp_hrd_parameters(struct rbsp *rbsp,
struct nal_h264_hrd_parameters *hrd)
{
unsigned int i;
if (!hrd) {
rbsp->error = -EINVAL;
return;
}
rbsp_uev(rbsp, &hrd->cpb_cnt_minus1);
rbsp_bits(rbsp, 4, &hrd->bit_rate_scale);
rbsp_bits(rbsp, 4, &hrd->cpb_size_scale);
for (i = 0; i <= hrd->cpb_cnt_minus1; i++) {
rbsp_uev(rbsp, &hrd->bit_rate_value_minus1[i]);
rbsp_uev(rbsp, &hrd->cpb_size_value_minus1[i]);
rbsp_bit(rbsp, &hrd->cbr_flag[i]);
}
rbsp_bits(rbsp, 5, &hrd->initial_cpb_removal_delay_length_minus1);
rbsp_bits(rbsp, 5, &hrd->cpb_removal_delay_length_minus1);
rbsp_bits(rbsp, 5, &hrd->dpb_output_delay_length_minus1);
rbsp_bits(rbsp, 5, &hrd->time_offset_length);
}
static void nal_h264_rbsp_vui_parameters(struct rbsp *rbsp,
struct nal_h264_vui_parameters *vui)
{
if (!vui) {
rbsp->error = -EINVAL;
return;
}
rbsp_bit(rbsp, &vui->aspect_ratio_info_present_flag);
if (vui->aspect_ratio_info_present_flag) {
rbsp_bits(rbsp, 8, &vui->aspect_ratio_idc);
if (vui->aspect_ratio_idc == 255) {
rbsp_bits(rbsp, 16, &vui->sar_width);
rbsp_bits(rbsp, 16, &vui->sar_height);
}
}
rbsp_bit(rbsp, &vui->overscan_info_present_flag);
if (vui->overscan_info_present_flag)
rbsp_bit(rbsp, &vui->overscan_appropriate_flag);
rbsp_bit(rbsp, &vui->video_signal_type_present_flag);
if (vui->video_signal_type_present_flag) {
rbsp_bits(rbsp, 3, &vui->video_format);
rbsp_bit(rbsp, &vui->video_full_range_flag);
rbsp_bit(rbsp, &vui->colour_description_present_flag);
if (vui->colour_description_present_flag) {
rbsp_bits(rbsp, 8, &vui->colour_primaries);
rbsp_bits(rbsp, 8, &vui->transfer_characteristics);
rbsp_bits(rbsp, 8, &vui->matrix_coefficients);
}
}
rbsp_bit(rbsp, &vui->chroma_loc_info_present_flag);
if (vui->chroma_loc_info_present_flag) {
rbsp_uev(rbsp, &vui->chroma_sample_loc_type_top_field);
rbsp_uev(rbsp, &vui->chroma_sample_loc_type_bottom_field);
}
rbsp_bit(rbsp, &vui->timing_info_present_flag);
if (vui->timing_info_present_flag) {
rbsp_bits(rbsp, 32, &vui->num_units_in_tick);
rbsp_bits(rbsp, 32, &vui->time_scale);
rbsp_bit(rbsp, &vui->fixed_frame_rate_flag);
}
rbsp_bit(rbsp, &vui->nal_hrd_parameters_present_flag);
if (vui->nal_hrd_parameters_present_flag)
nal_h264_rbsp_hrd_parameters(rbsp, &vui->nal_hrd_parameters);
rbsp_bit(rbsp, &vui->vcl_hrd_parameters_present_flag);
if (vui->vcl_hrd_parameters_present_flag)
nal_h264_rbsp_hrd_parameters(rbsp, &vui->vcl_hrd_parameters);
if (vui->nal_hrd_parameters_present_flag ||
vui->vcl_hrd_parameters_present_flag)
rbsp_bit(rbsp, &vui->low_delay_hrd_flag);
rbsp_bit(rbsp, &vui->pic_struct_present_flag);
rbsp_bit(rbsp, &vui->bitstream_restriction_flag);
if (vui->bitstream_restriction_flag) {
rbsp_bit(rbsp, &vui->motion_vectors_over_pic_boundaries_flag);
rbsp_uev(rbsp, &vui->max_bytes_per_pic_denom);
rbsp_uev(rbsp, &vui->max_bits_per_mb_denom);
rbsp_uev(rbsp, &vui->log2_max_mv_length_horizontal);
rbsp_uev(rbsp, &vui->log21_max_mv_length_vertical);
rbsp_uev(rbsp, &vui->max_num_reorder_frames);
rbsp_uev(rbsp, &vui->max_dec_frame_buffering);
}
}
static void nal_h264_rbsp_sps(struct rbsp *rbsp, struct nal_h264_sps *sps)
{
unsigned int i;
if (!sps) {
rbsp->error = -EINVAL;
return;
}
rbsp_bits(rbsp, 8, &sps->profile_idc);
rbsp_bit(rbsp, &sps->constraint_set0_flag);
rbsp_bit(rbsp, &sps->constraint_set1_flag);
rbsp_bit(rbsp, &sps->constraint_set2_flag);
rbsp_bit(rbsp, &sps->constraint_set3_flag);
rbsp_bit(rbsp, &sps->constraint_set4_flag);
rbsp_bit(rbsp, &sps->constraint_set5_flag);
rbsp_bits(rbsp, 2, &sps->reserved_zero_2bits);
rbsp_bits(rbsp, 8, &sps->level_idc);
rbsp_uev(rbsp, &sps->seq_parameter_set_id);
if (sps->profile_idc == 100 || sps->profile_idc == 110 ||
sps->profile_idc == 122 || sps->profile_idc == 244 ||
sps->profile_idc == 44 || sps->profile_idc == 83 ||
sps->profile_idc == 86 || sps->profile_idc == 118 ||
sps->profile_idc == 128 || sps->profile_idc == 138 ||
sps->profile_idc == 139 || sps->profile_idc == 134 ||
sps->profile_idc == 135) {
rbsp_uev(rbsp, &sps->chroma_format_idc);
if (sps->chroma_format_idc == 3)
rbsp_bit(rbsp, &sps->separate_colour_plane_flag);
rbsp_uev(rbsp, &sps->bit_depth_luma_minus8);
rbsp_uev(rbsp, &sps->bit_depth_chroma_minus8);
rbsp_bit(rbsp, &sps->qpprime_y_zero_transform_bypass_flag);
rbsp_bit(rbsp, &sps->seq_scaling_matrix_present_flag);
if (sps->seq_scaling_matrix_present_flag)
rbsp->error = -EINVAL;
}
rbsp_uev(rbsp, &sps->log2_max_frame_num_minus4);
rbsp_uev(rbsp, &sps->pic_order_cnt_type);
switch (sps->pic_order_cnt_type) {
case 0:
rbsp_uev(rbsp, &sps->log2_max_pic_order_cnt_lsb_minus4);
break;
case 1:
rbsp_bit(rbsp, &sps->delta_pic_order_always_zero_flag);
rbsp_sev(rbsp, &sps->offset_for_non_ref_pic);
rbsp_sev(rbsp, &sps->offset_for_top_to_bottom_field);
rbsp_uev(rbsp, &sps->num_ref_frames_in_pic_order_cnt_cycle);
for (i = 0; i < sps->num_ref_frames_in_pic_order_cnt_cycle; i++)
rbsp_sev(rbsp, &sps->offset_for_ref_frame[i]);
break;
default:
rbsp->error = -EINVAL;
break;
}
rbsp_uev(rbsp, &sps->max_num_ref_frames);
rbsp_bit(rbsp, &sps->gaps_in_frame_num_value_allowed_flag);
rbsp_uev(rbsp, &sps->pic_width_in_mbs_minus1);
rbsp_uev(rbsp, &sps->pic_height_in_map_units_minus1);
rbsp_bit(rbsp, &sps->frame_mbs_only_flag);
if (!sps->frame_mbs_only_flag)
rbsp_bit(rbsp, &sps->mb_adaptive_frame_field_flag);
rbsp_bit(rbsp, &sps->direct_8x8_inference_flag);
rbsp_bit(rbsp, &sps->frame_cropping_flag);
if (sps->frame_cropping_flag) {
rbsp_uev(rbsp, &sps->crop_left);
rbsp_uev(rbsp, &sps->crop_right);
rbsp_uev(rbsp, &sps->crop_top);
rbsp_uev(rbsp, &sps->crop_bottom);
}
rbsp_bit(rbsp, &sps->vui_parameters_present_flag);
if (sps->vui_parameters_present_flag)
nal_h264_rbsp_vui_parameters(rbsp, &sps->vui);
}
static void nal_h264_rbsp_pps(struct rbsp *rbsp, struct nal_h264_pps *pps)
{
int i;
rbsp_uev(rbsp, &pps->pic_parameter_set_id);
rbsp_uev(rbsp, &pps->seq_parameter_set_id);
rbsp_bit(rbsp, &pps->entropy_coding_mode_flag);
rbsp_bit(rbsp, &pps->bottom_field_pic_order_in_frame_present_flag);
rbsp_uev(rbsp, &pps->num_slice_groups_minus1);
if (pps->num_slice_groups_minus1 > 0) {
rbsp_uev(rbsp, &pps->slice_group_map_type);
switch (pps->slice_group_map_type) {
case 0:
for (i = 0; i < pps->num_slice_groups_minus1; i++)
rbsp_uev(rbsp, &pps->run_length_minus1[i]);
break;
case 2:
for (i = 0; i < pps->num_slice_groups_minus1; i++) {
rbsp_uev(rbsp, &pps->top_left[i]);
rbsp_uev(rbsp, &pps->bottom_right[i]);
}
break;
case 3: case 4: case 5:
rbsp_bit(rbsp, &pps->slice_group_change_direction_flag);
rbsp_uev(rbsp, &pps->slice_group_change_rate_minus1);
break;
case 6:
rbsp_uev(rbsp, &pps->pic_size_in_map_units_minus1);
for (i = 0; i < pps->pic_size_in_map_units_minus1; i++)
rbsp_bits(rbsp,
order_base_2(pps->num_slice_groups_minus1 + 1),
&pps->slice_group_id[i]);
break;
default:
break;
}
}
rbsp_uev(rbsp, &pps->num_ref_idx_l0_default_active_minus1);
rbsp_uev(rbsp, &pps->num_ref_idx_l1_default_active_minus1);
rbsp_bit(rbsp, &pps->weighted_pred_flag);
rbsp_bits(rbsp, 2, &pps->weighted_bipred_idc);
rbsp_sev(rbsp, &pps->pic_init_qp_minus26);
rbsp_sev(rbsp, &pps->pic_init_qs_minus26);
rbsp_sev(rbsp, &pps->chroma_qp_index_offset);
rbsp_bit(rbsp, &pps->deblocking_filter_control_present_flag);
rbsp_bit(rbsp, &pps->constrained_intra_pred_flag);
rbsp_bit(rbsp, &pps->redundant_pic_cnt_present_flag);
if (/* more_rbsp_data() */ false) {
rbsp_bit(rbsp, &pps->transform_8x8_mode_flag);
rbsp_bit(rbsp, &pps->pic_scaling_matrix_present_flag);
if (pps->pic_scaling_matrix_present_flag)
rbsp->error = -EINVAL;
rbsp_sev(rbsp, &pps->second_chroma_qp_index_offset);
}
}
/**
* nal_h264_write_sps() - Write SPS NAL unit into RBSP format
* @dev: device pointer
* @dest: the buffer that is filled with RBSP data
* @n: maximum size of @dest in bytes
* @sps: &struct nal_h264_sps to convert to RBSP
*
* Convert @sps to RBSP data and write it into @dest.
*
* The size of the SPS NAL unit is not known in advance and this function will
* fail, if @dest does not hold sufficient space for the SPS NAL unit.
*
* Return: number of bytes written to @dest or negative error code
*/
ssize_t nal_h264_write_sps(const struct device *dev,
void *dest, size_t n, struct nal_h264_sps *sps)
{
struct rbsp rbsp;
unsigned int forbidden_zero_bit = 0;
unsigned int nal_ref_idc = 0;
unsigned int nal_unit_type = SEQUENCE_PARAMETER_SET;
if (!dest)
return -EINVAL;
rbsp_init(&rbsp, dest, n, &write);
nal_h264_write_start_code_prefix(&rbsp);
rbsp_bit(&rbsp, &forbidden_zero_bit);
rbsp_bits(&rbsp, 2, &nal_ref_idc);
rbsp_bits(&rbsp, 5, &nal_unit_type);
nal_h264_rbsp_sps(&rbsp, sps);
rbsp_trailing_bits(&rbsp);
if (rbsp.error)
return rbsp.error;
return DIV_ROUND_UP(rbsp.pos, 8);
}
EXPORT_SYMBOL_GPL(nal_h264_write_sps);
/**
* nal_h264_read_sps() - Read SPS NAL unit from RBSP format
* @dev: device pointer
* @sps: the &struct nal_h264_sps to fill from the RBSP data
* @src: the buffer that contains the RBSP data
* @n: size of @src in bytes
*
* Read RBSP data from @src and use it to fill @sps.
*
* Return: number of bytes read from @src or negative error code
*/
ssize_t nal_h264_read_sps(const struct device *dev,
struct nal_h264_sps *sps, void *src, size_t n)
{
struct rbsp rbsp;
unsigned int forbidden_zero_bit;
unsigned int nal_ref_idc;
unsigned int nal_unit_type;
if (!src)
return -EINVAL;
rbsp_init(&rbsp, src, n, &read);
nal_h264_read_start_code_prefix(&rbsp);
rbsp_bit(&rbsp, &forbidden_zero_bit);
rbsp_bits(&rbsp, 2, &nal_ref_idc);
rbsp_bits(&rbsp, 5, &nal_unit_type);
if (rbsp.error ||
forbidden_zero_bit != 0 ||
nal_ref_idc != 0 ||
nal_unit_type != SEQUENCE_PARAMETER_SET)
return -EINVAL;
nal_h264_rbsp_sps(&rbsp, sps);
rbsp_trailing_bits(&rbsp);
if (rbsp.error)
return rbsp.error;
return DIV_ROUND_UP(rbsp.pos, 8);
}
EXPORT_SYMBOL_GPL(nal_h264_read_sps);
/**
* nal_h264_write_pps() - Write PPS NAL unit into RBSP format
* @dev: device pointer
* @dest: the buffer that is filled with RBSP data
* @n: maximum size of @dest in bytes
* @pps: &struct nal_h264_pps to convert to RBSP
*
* Convert @pps to RBSP data and write it into @dest.
*
* The size of the PPS NAL unit is not known in advance and this function will
* fail, if @dest does not hold sufficient space for the PPS NAL unit.
*
* Return: number of bytes written to @dest or negative error code
*/
ssize_t nal_h264_write_pps(const struct device *dev,
void *dest, size_t n, struct nal_h264_pps *pps)
{
struct rbsp rbsp;
unsigned int forbidden_zero_bit = 0;
unsigned int nal_ref_idc = 0;
unsigned int nal_unit_type = PICTURE_PARAMETER_SET;
if (!dest)
return -EINVAL;
rbsp_init(&rbsp, dest, n, &write);
nal_h264_write_start_code_prefix(&rbsp);
/* NAL unit header */
rbsp_bit(&rbsp, &forbidden_zero_bit);
rbsp_bits(&rbsp, 2, &nal_ref_idc);
rbsp_bits(&rbsp, 5, &nal_unit_type);
nal_h264_rbsp_pps(&rbsp, pps);
rbsp_trailing_bits(&rbsp);
if (rbsp.error)
return rbsp.error;
return DIV_ROUND_UP(rbsp.pos, 8);
}
EXPORT_SYMBOL_GPL(nal_h264_write_pps);
/**
* nal_h264_read_pps() - Read PPS NAL unit from RBSP format
* @dev: device pointer
* @pps: the &struct nal_h264_pps to fill from the RBSP data
* @src: the buffer that contains the RBSP data
* @n: size of @src in bytes
*
* Read RBSP data from @src and use it to fill @pps.
*
* Return: number of bytes read from @src or negative error code
*/
ssize_t nal_h264_read_pps(const struct device *dev,
struct nal_h264_pps *pps, void *src, size_t n)
{
struct rbsp rbsp;
if (!src)
return -EINVAL;
rbsp_init(&rbsp, src, n, &read);
nal_h264_read_start_code_prefix(&rbsp);
/* NAL unit header */
rbsp.pos += 8;
nal_h264_rbsp_pps(&rbsp, pps);
rbsp_trailing_bits(&rbsp);
if (rbsp.error)
return rbsp.error;
return DIV_ROUND_UP(rbsp.pos, 8);
}
EXPORT_SYMBOL_GPL(nal_h264_read_pps);
/**
* nal_h264_write_filler() - Write filler data RBSP
* @dev: device pointer
* @dest: buffer to fill with filler data
* @n: size of the buffer to fill with filler data
*
* Write a filler data RBSP to @dest with a size of @n bytes and return the
* number of written filler data bytes.
*
* Use this function to generate dummy data in an RBSP data stream that can be
* safely ignored by h264 decoders.
*
* The RBSP format of the filler data is specified in Rec. ITU-T H.264
* (04/2017) 7.3.2.7 Filler data RBSP syntax.
*
* Return: number of filler data bytes (including marker) or negative error
*/
ssize_t nal_h264_write_filler(const struct device *dev, void *dest, size_t n)
{
struct rbsp rbsp;
unsigned int forbidden_zero_bit = 0;
unsigned int nal_ref_idc = 0;
unsigned int nal_unit_type = FILLER_DATA;
if (!dest)
return -EINVAL;
rbsp_init(&rbsp, dest, n, &write);
nal_h264_write_start_code_prefix(&rbsp);
rbsp_bit(&rbsp, &forbidden_zero_bit);
rbsp_bits(&rbsp, 2, &nal_ref_idc);
rbsp_bits(&rbsp, 5, &nal_unit_type);
nal_h264_write_filler_data(&rbsp);
rbsp_trailing_bits(&rbsp);
return DIV_ROUND_UP(rbsp.pos, 8);
}
EXPORT_SYMBOL_GPL(nal_h264_write_filler);
/**
* nal_h264_read_filler() - Read filler data RBSP
* @dev: device pointer
* @src: buffer with RBSP data that is read
* @n: maximum size of src that shall be read
*
* Read a filler data RBSP from @src up to a maximum size of @n bytes and
* return the size of the filler data in bytes including the marker.
*
* This function is used to parse filler data and skip the respective bytes in
* the RBSP data.
*
* The RBSP format of the filler data is specified in Rec. ITU-T H.264
* (04/2017) 7.3.2.7 Filler data RBSP syntax.
*
* Return: number of filler data bytes (including marker) or negative error
*/
ssize_t nal_h264_read_filler(const struct device *dev, void *src, size_t n)
{
struct rbsp rbsp;
unsigned int forbidden_zero_bit;
unsigned int nal_ref_idc;
unsigned int nal_unit_type;
if (!src)
return -EINVAL;
rbsp_init(&rbsp, src, n, &read);
nal_h264_read_start_code_prefix(&rbsp);
rbsp_bit(&rbsp, &forbidden_zero_bit);
rbsp_bits(&rbsp, 2, &nal_ref_idc);
rbsp_bits(&rbsp, 5, &nal_unit_type);
if (rbsp.error)
return rbsp.error;
if (forbidden_zero_bit != 0 ||
nal_ref_idc != 0 ||
nal_unit_type != FILLER_DATA)
return -EINVAL;
nal_h264_read_filler_data(&rbsp);
rbsp_trailing_bits(&rbsp);
if (rbsp.error)
return rbsp.error;
return DIV_ROUND_UP(rbsp.pos, 8);
}
EXPORT_SYMBOL_GPL(nal_h264_read_filler);