1.16. Stateless Codec Control Reference

The Stateless Codec control class is intended to support stateless decoder and encoders (i.e. hardware accelerators).

These drivers are typically supported by the Memory-to-memory Stateless Video Decoder Interface, and deal with parsed pixel formats such as V4L2_PIX_FMT_H264_SLICE.

1.16.1. Stateless Codec Control ID

V4L2_CID_CODEC_STATELESS_CLASS (class)

The Stateless Codec class descriptor.

V4L2_CID_STATELESS_H264_SPS (struct)

Specifies the sequence parameter set (as extracted from the bitstream) for the associated H264 slice data. This includes the necessary parameters for configuring a stateless hardware decoding pipeline for H264. The bitstream parameters are defined according to ITU-T Rec. H.264 Specification (04/2017 Edition), section 7.4.2.1.1 “Sequence Parameter Set Data Semantics”. For further documentation, refer to the above specification, unless there is an explicit comment stating otherwise.

type v4l2_ctrl_h264_sps

struct v4l2_ctrl_h264_sps

__u8	profile_idc
__u8	constraint_set_flags	See Sequence Parameter Set Constraints Set Flags
__u8	level_idc
__u8	seq_parameter_set_id
__u8	chroma_format_idc
__u8	bit_depth_luma_minus8
__u8	bit_depth_chroma_minus8
__u8	log2_max_frame_num_minus4
__u8	pic_order_cnt_type
__u8	log2_max_pic_order_cnt_lsb_minus4
__u8	max_num_ref_frames
__u8	num_ref_frames_in_pic_order_cnt_cycle
__s32	offset_for_ref_frame[255]
__s32	offset_for_non_ref_pic
__s32	offset_for_top_to_bottom_field
__u16	pic_width_in_mbs_minus1
__u16	pic_height_in_map_units_minus1
__u32	flags	See Sequence Parameter Set Flags

Sequence Parameter Set Constraints Set Flags

V4L2_H264_SPS_CONSTRAINT_SET0_FLAG	0x00000001
V4L2_H264_SPS_CONSTRAINT_SET1_FLAG	0x00000002
V4L2_H264_SPS_CONSTRAINT_SET2_FLAG	0x00000004
V4L2_H264_SPS_CONSTRAINT_SET3_FLAG	0x00000008
V4L2_H264_SPS_CONSTRAINT_SET4_FLAG	0x00000010
V4L2_H264_SPS_CONSTRAINT_SET5_FLAG	0x00000020

Sequence Parameter Set Flags

V4L2_H264_SPS_FLAG_SEPARATE_COLOUR_PLANE	0x00000001
V4L2_H264_SPS_FLAG_QPPRIME_Y_ZERO_TRANSFORM_BYPASS	0x00000002
V4L2_H264_SPS_FLAG_DELTA_PIC_ORDER_ALWAYS_ZERO	0x00000004
V4L2_H264_SPS_FLAG_GAPS_IN_FRAME_NUM_VALUE_ALLOWED	0x00000008
V4L2_H264_SPS_FLAG_FRAME_MBS_ONLY	0x00000010
V4L2_H264_SPS_FLAG_MB_ADAPTIVE_FRAME_FIELD	0x00000020
V4L2_H264_SPS_FLAG_DIRECT_8X8_INFERENCE	0x00000040

V4L2_CID_STATELESS_H264_PPS (struct)

Specifies the picture parameter set (as extracted from the bitstream) for the associated H264 slice data. This includes the necessary parameters for configuring a stateless hardware decoding pipeline for H264. The bitstream parameters are defined according to ITU-T Rec. H.264 Specification (04/2017 Edition), section 7.4.2.2 “Picture Parameter Set RBSP Semantics”. For further documentation, refer to the above specification, unless there is an explicit comment stating otherwise.

type v4l2_ctrl_h264_pps

struct v4l2_ctrl_h264_pps

__u8	pic_parameter_set_id
__u8	seq_parameter_set_id
__u8	num_slice_groups_minus1
__u8	num_ref_idx_l0_default_active_minus1
__u8	num_ref_idx_l1_default_active_minus1
__u8	weighted_bipred_idc
__s8	pic_init_qp_minus26
__s8	pic_init_qs_minus26
__s8	chroma_qp_index_offset
__s8	second_chroma_qp_index_offset
__u16	flags	See Picture Parameter Set Flags

Picture Parameter Set Flags

V4L2_H264_PPS_FLAG_ENTROPY_CODING_MODE	0x0001
V4L2_H264_PPS_FLAG_BOTTOM_FIELD_PIC_ORDER_IN_FRAME_PRESENT	0x0002
V4L2_H264_PPS_FLAG_WEIGHTED_PRED	0x0004
V4L2_H264_PPS_FLAG_DEBLOCKING_FILTER_CONTROL_PRESENT	0x0008
V4L2_H264_PPS_FLAG_CONSTRAINED_INTRA_PRED	0x0010
V4L2_H264_PPS_FLAG_REDUNDANT_PIC_CNT_PRESENT	0x0020
V4L2_H264_PPS_FLAG_TRANSFORM_8X8_MODE	0x0040
V4L2_H264_PPS_FLAG_SCALING_MATRIX_PRESENT	0x0080	V4L2_CID_STATELESS_H264_SCALING_MATRIX must be used for this picture.

V4L2_CID_STATELESS_H264_SCALING_MATRIX (struct)

Specifies the scaling matrix (as extracted from the bitstream) for the associated H264 slice data. The bitstream parameters are defined according to ITU-T Rec. H.264 Specification (04/2017 Edition), section 7.4.2.1.1.1 “Scaling List Semantics”. For further documentation, refer to the above specification, unless there is an explicit comment stating otherwise.

type v4l2_ctrl_h264_scaling_matrix

struct v4l2_ctrl_h264_scaling_matrix

__u8	scaling_list_4x4[6][16]	Scaling matrix after applying the inverse scanning process. Expected list order is Intra Y, Intra Cb, Intra Cr, Inter Y, Inter Cb, Inter Cr. The values on each scaling list are expected in raster scan order.
__u8	scaling_list_8x8[6][64]	Scaling matrix after applying the inverse scanning process. Expected list order is Intra Y, Inter Y, Intra Cb, Inter Cb, Intra Cr, Inter Cr. The values on each scaling list are expected in raster scan order.

V4L2_CID_STATELESS_H264_SLICE_PARAMS (struct)

Specifies the slice parameters (as extracted from the bitstream) for the associated H264 slice data. This includes the necessary parameters for configuring a stateless hardware decoding pipeline for H264. The bitstream parameters are defined according to ITU-T Rec. H.264 Specification (04/2017 Edition), section 7.4.3 “Slice Header Semantics”. For further documentation, refer to the above specification, unless there is an explicit comment stating otherwise.

type v4l2_ctrl_h264_slice_params

struct v4l2_ctrl_h264_slice_params

__u32	header_bit_size	Offset in bits to slice_data() from the beginning of this slice.
__u32	first_mb_in_slice
__u8	slice_type
__u8	colour_plane_id
__u8	redundant_pic_cnt
__u8	cabac_init_idc
__s8	slice_qp_delta
__s8	slice_qs_delta
__u8	disable_deblocking_filter_idc
__s8	slice_alpha_c0_offset_div2
__s8	slice_beta_offset_div2
__u8	num_ref_idx_l0_active_minus1	If num_ref_idx_active_override_flag is not set, this field must be set to the value of num_ref_idx_l0_default_active_minus1
__u8	num_ref_idx_l1_active_minus1	If num_ref_idx_active_override_flag is not set, this field must be set to the value of num_ref_idx_l1_default_active_minus1
__u8	reserved	Applications and drivers must set this to zero.
struct v4l2_h264_reference	ref_pic_list0[32]	Reference picture list after applying the per-slice modifications
struct v4l2_h264_reference	ref_pic_list1[32]	Reference picture list after applying the per-slice modifications
__u32	flags	See Slice Parameter Flags

Slice Parameter Set Flags

V4L2_H264_SLICE_FLAG_DIRECT_SPATIAL_MV_PRED	0x00000001
V4L2_H264_SLICE_FLAG_SP_FOR_SWITCH	0x00000002

V4L2_CID_STATELESS_H264_PRED_WEIGHTS (struct)

Prediction weight table defined according to ITU-T Rec. H.264 Specification (04/2017 Edition), section 7.4.3.2 “Prediction Weight Table Semantics”. The prediction weight table must be passed by applications under the conditions explained in section 7.3.3 “Slice header syntax”.

type v4l2_ctrl_h264_pred_weights

struct v4l2_ctrl_h264_pred_weights

__u16	luma_log2_weight_denom
__u16	chroma_log2_weight_denom
struct v4l2_h264_weight_factors	weight_factors[2]	The weight factors at index 0 are the weight factors for the reference list 0, the one at index 1 for the reference list 1.

type v4l2_h264_weight_factors

struct v4l2_h264_weight_factors

__s16	luma_weight[32]
__s16	luma_offset[32]
__s16	chroma_weight[32][2]
__s16	chroma_offset[32][2]

Picture Reference

type v4l2_h264_reference

struct v4l2_h264_reference

__u8	fields	Specifies how the picture is referenced. See Reference Fields
__u8	index	Index into the v4l2_ctrl_h264_decode_params.dpb array.

Reference Fields

V4L2_H264_TOP_FIELD_REF	0x1	The top field in field pair is used for short-term reference.
V4L2_H264_BOTTOM_FIELD_REF	0x2	The bottom field in field pair is used for short-term reference.
V4L2_H264_FRAME_REF	0x3	The frame (or the top/bottom fields, if it’s a field pair) is used for short-term reference.

V4L2_CID_STATELESS_H264_DECODE_PARAMS (struct)

Specifies the decode parameters (as extracted from the bitstream) for the associated H264 slice data. This includes the necessary parameters for configuring a stateless hardware decoding pipeline for H264. The bitstream parameters are defined according to ITU-T Rec. H.264 Specification (04/2017 Edition). For further documentation, refer to the above specification, unless there is an explicit comment stating otherwise.

type v4l2_ctrl_h264_decode_params

struct v4l2_ctrl_h264_decode_params

struct v4l2_h264_dpb_entry	dpb[16]
__u16	nal_ref_idc	NAL reference ID value coming from the NAL Unit header
__u16	frame_num
__s32	top_field_order_cnt	Picture Order Count for the coded top field
__s32	bottom_field_order_cnt	Picture Order Count for the coded bottom field
__u16	idr_pic_id
__u16	pic_order_cnt_lsb
__s32	delta_pic_order_cnt_bottom
__s32	delta_pic_order_cnt0
__s32	delta_pic_order_cnt1
__u32	dec_ref_pic_marking_bit_size	Size in bits of the dec_ref_pic_marking() syntax element.
__u32	pic_order_cnt_bit_size	Combined size in bits of the picture order count related syntax elements: pic_order_cnt_lsb, delta_pic_order_cnt_bottom, delta_pic_order_cnt0, and delta_pic_order_cnt1.
__u32	slice_group_change_cycle
__u32	reserved	Applications and drivers must set this to zero.
__u32	flags	See Decode Parameters Flags

Decode Parameters Flags

V4L2_H264_DECODE_PARAM_FLAG_IDR_PIC	0x00000001	That picture is an IDR picture
V4L2_H264_DECODE_PARAM_FLAG_FIELD_PIC	0x00000002
V4L2_H264_DECODE_PARAM_FLAG_BOTTOM_FIELD	0x00000004

type v4l2_h264_dpb_entry

struct v4l2_h264_dpb_entry

__u64	reference_ts	Timestamp of the V4L2 capture buffer to use as reference, used with B-coded and P-coded frames. The timestamp refers to the timestamp field in struct v4l2_buffer. Use the v4l2_timeval_to_ns() function to convert the struct timeval in struct v4l2_buffer to a __u64.
__u32	pic_num
__u16	frame_num
__u8	fields	Specifies how the DPB entry is referenced. See Reference Fields
__u8	reserved[5]	Applications and drivers must set this to zero.
__s32	top_field_order_cnt
__s32	bottom_field_order_cnt
__u32	flags	See DPB Entry Flags

DPB Entries Flags

V4L2_H264_DPB_ENTRY_FLAG_VALID	0x00000001	The DPB entry is valid (non-empty) and should be considered.
V4L2_H264_DPB_ENTRY_FLAG_ACTIVE	0x00000002	The DPB entry is used for reference.
V4L2_H264_DPB_ENTRY_FLAG_LONG_TERM	0x00000004	The DPB entry is used for long-term reference.
V4L2_H264_DPB_ENTRY_FLAG_FIELD	0x00000008	The DPB entry is a single field or a complementary field pair.

V4L2_CID_STATELESS_H264_DECODE_MODE (enum)

Specifies the decoding mode to use. Currently exposes slice-based and frame-based decoding but new modes might be added later on. This control is used as a modifier for V4L2_PIX_FMT_H264_SLICE pixel format. Applications that support V4L2_PIX_FMT_H264_SLICE are required to set this control in order to specify the decoding mode that is expected for the buffer. Drivers may expose a single or multiple decoding modes, depending on what they can support.

type v4l2_stateless_h264_decode_mode

V4L2_STATELESS_H264_DECODE_MODE_SLICE_BASED	0	Decoding is done at the slice granularity. The OUTPUT buffer must contain a single slice. When this mode is selected, the V4L2_CID_STATELESS_H264_SLICE_PARAMS control shall be set. When multiple slices compose a frame, use of V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF flag is required.
V4L2_STATELESS_H264_DECODE_MODE_FRAME_BASED	1	Decoding is done at the frame granularity, The OUTPUT buffer must contain all slices needed to decode the frame. The OUTPUT buffer must also contain both fields. This mode will be supported by devices that parse the slice(s) header(s) in hardware. When this mode is selected, the V4L2_CID_STATELESS_H264_SLICE_PARAMS control shall not be set.

V4L2_CID_STATELESS_H264_START_CODE (enum)

Specifies the H264 slice start code expected for each slice. This control is used as a modifier for V4L2_PIX_FMT_H264_SLICE pixel format. Applications that support V4L2_PIX_FMT_H264_SLICE are required to set this control in order to specify the start code that is expected for the buffer. Drivers may expose a single or multiple start codes, depending on what they can support.

type v4l2_stateless_h264_start_code

V4L2_STATELESS_H264_START_CODE_NONE	0	Selecting this value specifies that H264 slices are passed to the driver without any start code. The bitstream data should be according to ITU-T Rec. H.264 Specification (04/2017 Edition) 7.3.1 NAL unit syntax, hence contains emulation prevention bytes when required.
V4L2_STATELESS_H264_START_CODE_ANNEX_B	1	Selecting this value specifies that H264 slices are expected to be prefixed by Annex B start codes. According to ITU-T Rec. H.264 Specification (04/2017 Edition) valid start codes can be 3-bytes 0x000001 or 4-bytes 0x00000001.

V4L2_CID_STATELESS_FWHT_PARAMS (struct)

Specifies the FWHT (Fast Walsh Hadamard Transform) parameters (as extracted from the bitstream) for the associated FWHT data. This includes the necessary parameters for configuring a stateless hardware decoding pipeline for FWHT. This codec is specific to the vicodec test driver.

type v4l2_ctrl_fwht_params

struct v4l2_ctrl_fwht_params

__u64	backward_ref_ts	Timestamp of the V4L2 capture buffer to use as backward reference, used with P-coded frames. The timestamp refers to the timestamp field in struct v4l2_buffer. Use the v4l2_timeval_to_ns() function to convert the struct timeval in struct v4l2_buffer to a __u64.
__u32	version	The version of the codec. Set to V4L2_FWHT_VERSION.
__u32	width	The width of the frame.
__u32	height	The height of the frame.
__u32	flags	The flags of the frame, see FWHT Flags.
__u32	colorspace	The colorspace of the frame, from enum v4l2_colorspace.
__u32	xfer_func	The transfer function, from enum v4l2_xfer_func.
__u32	ycbcr_enc	The Y’CbCr encoding, from enum v4l2_ycbcr_encoding.
__u32	quantization	The quantization range, from enum v4l2_quantization.

1.16.2. FWHT Flags

V4L2_FWHT_FL_IS_INTERLACED	0x00000001	Set if this is an interlaced format.
V4L2_FWHT_FL_IS_BOTTOM_FIRST	0x00000002	Set if this is a bottom-first (NTSC) interlaced format.
V4L2_FWHT_FL_IS_ALTERNATE	0x00000004	Set if each ‘frame’ contains just one field.
V4L2_FWHT_FL_IS_BOTTOM_FIELD	0x00000008	If V4L2_FWHT_FL_IS_ALTERNATE was set, then this is set if this ‘frame’ is the bottom field, else it is the top field.
V4L2_FWHT_FL_LUMA_IS_UNCOMPRESSED	0x00000010	Set if the Y’ (luma) plane is uncompressed.
V4L2_FWHT_FL_CB_IS_UNCOMPRESSED	0x00000020	Set if the Cb plane is uncompressed.
V4L2_FWHT_FL_CR_IS_UNCOMPRESSED	0x00000040	Set if the Cr plane is uncompressed.
V4L2_FWHT_FL_CHROMA_FULL_HEIGHT	0x00000080	Set if the chroma plane has the same height as the luma plane, else the chroma plane is half the height of the luma plane.
V4L2_FWHT_FL_CHROMA_FULL_WIDTH	0x00000100	Set if the chroma plane has the same width as the luma plane, else the chroma plane is half the width of the luma plane.
V4L2_FWHT_FL_ALPHA_IS_UNCOMPRESSED	0x00000200	Set if the alpha plane is uncompressed.
V4L2_FWHT_FL_I_FRAME	0x00000400	Set if this is an I-frame.
V4L2_FWHT_FL_COMPONENTS_NUM_MSK	0x00070000	The number of color components minus one.
V4L2_FWHT_FL_PIXENC_MSK	0x00180000	The mask for the pixel encoding.
V4L2_FWHT_FL_PIXENC_YUV	0x00080000	Set if the pixel encoding is YUV.
V4L2_FWHT_FL_PIXENC_RGB	0x00100000	Set if the pixel encoding is RGB.
V4L2_FWHT_FL_PIXENC_HSV	0x00180000	Set if the pixel encoding is HSV.

V4L2_CID_STATELESS_VP8_FRAME (struct)

Specifies the frame parameters for the associated VP8 parsed frame data. This includes the necessary parameters for configuring a stateless hardware decoding pipeline for VP8. The bitstream parameters are defined according to VP8.

type v4l2_ctrl_vp8_frame

struct v4l2_ctrl_vp8_frame

struct v4l2_vp8_segment	segment	Structure with segment-based adjustments metadata.
struct v4l2_vp8_loop_filter	lf	Structure with loop filter level adjustments metadata.
struct v4l2_vp8_quantization	quant	Structure with VP8 dequantization indices metadata.
struct v4l2_vp8_entropy	entropy	Structure with VP8 entropy coder probabilities metadata.
struct v4l2_vp8_entropy_coder_state	coder_state	Structure with VP8 entropy coder state.
__u16	width	The width of the frame. Must be set for all frames.
__u16	height	The height of the frame. Must be set for all frames.
__u8	horizontal_scale	Horizontal scaling factor.
__u8	vertical_scaling factor	Vertical scale.
__u8	version	Bitstream version.
__u8	prob_skip_false	Indicates the probability that the macroblock is not skipped.
__u8	prob_intra	Indicates the probability that a macroblock is intra-predicted.
__u8	prob_last	Indicates the probability that the last reference frame is used for inter-prediction
__u8	prob_gf	Indicates the probability that the golden reference frame is used for inter-prediction
__u8	num_dct_parts	Number of DCT coefficients partitions. Must be one of: 1, 2, 4, or 8.
__u32	first_part_size	Size of the first partition, i.e. the control partition.
__u32	first_part_header_bits	Size in bits of the first partition header portion.
__u32	dct_part_sizes[8]	DCT coefficients sizes.
__u64	last_frame_ts	Timestamp for the V4L2 capture buffer to use as last reference frame, used with inter-coded frames. The timestamp refers to the timestamp field in struct v4l2_buffer. Use the v4l2_timeval_to_ns() function to convert the struct timeval in struct v4l2_buffer to a __u64.
__u64	golden_frame_ts	Timestamp for the V4L2 capture buffer to use as last reference frame, used with inter-coded frames. The timestamp refers to the timestamp field in struct v4l2_buffer. Use the v4l2_timeval_to_ns() function to convert the struct timeval in struct v4l2_buffer to a __u64.
__u64	alt_frame_ts	Timestamp for the V4L2 capture buffer to use as alternate reference frame, used with inter-coded frames. The timestamp refers to the timestamp field in struct v4l2_buffer. Use the v4l2_timeval_to_ns() function to convert the struct timeval in struct v4l2_buffer to a __u64.
__u64	flags	See Frame Flags

Frame Flags

V4L2_VP8_FRAME_FLAG_KEY_FRAME	0x01	Indicates if the frame is a key frame.
V4L2_VP8_FRAME_FLAG_EXPERIMENTAL	0x02	Experimental bitstream.
V4L2_VP8_FRAME_FLAG_SHOW_FRAME	0x04	Show frame flag, indicates if the frame is for display.
V4L2_VP8_FRAME_FLAG_MB_NO_SKIP_COEFF	0x08	Enable/disable skipping of macroblocks with no non-zero coefficients.
V4L2_VP8_FRAME_FLAG_SIGN_BIAS_GOLDEN	0x10	Sign of motion vectors when the golden frame is referenced.
V4L2_VP8_FRAME_FLAG_SIGN_BIAS_ALT	0x20	Sign of motion vectors when the alt frame is referenced.

type v4l2_vp8_entropy_coder_state

struct v4l2_vp8_entropy_coder_state

__u8	range	coder state value for “Range”
__u8	value	coder state value for “Value”-
__u8	bit_count	number of bits left.
__u8	padding	Applications and drivers must set this to zero.

type v4l2_vp8_segment

struct v4l2_vp8_segment

__s8	quant_update[4]	Signed quantizer value update.
__s8	lf_update[4]	Signed loop filter level value update.
__u8	segment_probs[3]	Segment probabilities.
__u8	padding	Applications and drivers must set this to zero.
__u32	flags	See Segment Flags

Segment Flags

V4L2_VP8_SEGMENT_FLAG_ENABLED	0x01	Enable/disable segment-based adjustments.
V4L2_VP8_SEGMENT_FLAG_UPDATE_MAP	0x02	Indicates if the macroblock segmentation map is updated in this frame.
V4L2_VP8_SEGMENT_FLAG_UPDATE_FEATURE_DATA	0x04	Indicates if the segment feature data is updated in this frame.
V4L2_VP8_SEGMENT_FLAG_DELTA_VALUE_MODE	0x08	If is set, the segment feature data mode is delta-value. If cleared, it’s absolute-value.

type v4l2_vp8_loop_filter

struct v4l2_vp8_loop_filter

__s8	ref_frm_delta[4]	Reference adjustment (signed) delta value.
__s8	mb_mode_delta[4]	Macroblock prediction mode adjustment (signed) delta value.
__u8	sharpness_level	Sharpness level
__u8	level	Filter level
__u16	padding	Applications and drivers must set this to zero.
__u32	flags	See Loop Filter Flags

Loop Filter Flags

V4L2_VP8_LF_ADJ_ENABLE	0x01	Enable/disable macroblock-level loop filter adjustment.
V4L2_VP8_LF_DELTA_UPDATE	0x02	Indicates if the delta values used in an adjustment are updated.
V4L2_VP8_LF_FILTER_TYPE_SIMPLE	0x04	If set, indicates the filter type is simple. If cleared, the filter type is normal.

type v4l2_vp8_quantization

struct v4l2_vp8_quantization

__u8	y_ac_qi	Luma AC coefficient table index.
__s8	y_dc_delta	Luma DC delta vaue.
__s8	y2_dc_delta	Y2 block DC delta value.
__s8	y2_ac_delta	Y2 block AC delta value.
__s8	uv_dc_delta	Chroma DC delta value.
__s8	uv_ac_delta	Chroma AC delta value.
__u16	padding	Applications and drivers must set this to zero.

type v4l2_vp8_entropy

struct v4l2_vp8_entropy

__u8	coeff_probs[4][8][3][11]	Coefficient update probabilities.
__u8	y_mode_probs[4]	Luma mode update probabilities.
__u8	uv_mode_probs[3]	Chroma mode update probabilities.
__u8	mv_probs[2][19]	MV decoding update probabilities.
__u8	padding[3]	Applications and drivers must set this to zero.

V4L2_CID_STATELESS_MPEG2_SEQUENCE (struct)

Specifies the sequence parameters (as extracted from the bitstream) for the associated MPEG-2 slice data. This includes fields matching the syntax elements from the sequence header and sequence extension parts of the bitstream as specified by ISO 13818-2.

type v4l2_ctrl_mpeg2_sequence

struct v4l2_ctrl_mpeg2_sequence

__u16	horizontal_size	The width of the displayable part of the frame’s luminance component.
__u16	vertical_size	The height of the displayable part of the frame’s luminance component.
__u32	vbv_buffer_size	Used to calculate the required size of the video buffering verifier, defined (in bits) as: 16 * 1024 * vbv_buffer_size.
__u16	profile_and_level_indication	The current profile and level indication as extracted from the bitstream.
__u8	chroma_format	The chrominance sub-sampling format (1: 4:2:0, 2: 4:2:2, 3: 4:4:4).
__u8	flags	See MPEG-2 Sequence Flags.

MPEG-2 Sequence Flags

V4L2_MPEG2_SEQ_FLAG_PROGRESSIVE

0x01

Indication that all the frames for the sequence are progressive instead of interlaced.

V4L2_CID_STATELESS_MPEG2_PICTURE (struct)

Specifies the picture parameters (as extracted from the bitstream) for the associated MPEG-2 slice data. This includes fields matching the syntax elements from the picture header and picture coding extension parts of the bitstream as specified by ISO 13818-2.

type v4l2_ctrl_mpeg2_picture

struct v4l2_ctrl_mpeg2_picture

__u64	backward_ref_ts	Timestamp of the V4L2 capture buffer to use as backward reference, used with B-coded and P-coded frames. The timestamp refers to the timestamp field in struct v4l2_buffer. Use the v4l2_timeval_to_ns() function to convert the struct timeval in struct v4l2_buffer to a __u64.
__u64	forward_ref_ts	Timestamp for the V4L2 capture buffer to use as forward reference, used with B-coded frames. The timestamp refers to the timestamp field in struct v4l2_buffer. Use the v4l2_timeval_to_ns() function to convert the struct timeval in struct v4l2_buffer to a __u64.
__u32	flags	See MPEG-2 Picture Flags.
__u8	f_code[2][2]	Motion vector codes.
__u8	picture_coding_type	Picture coding type for the frame covered by the current slice (V4L2_MPEG2_PIC_CODING_TYPE_I, V4L2_MPEG2_PIC_CODING_TYPE_P or V4L2_MPEG2_PIC_CODING_TYPE_B).
__u8	picture_structure	Picture structure (1: interlaced top field, 2: interlaced bottom field, 3: progressive frame).
__u8	intra_dc_precision	Precision of Discrete Cosine transform (0: 8 bits precision, 1: 9 bits precision, 2: 10 bits precision, 3: 11 bits precision).
__u8	reserved[5]	Applications and drivers must set this to zero.

MPEG-2 Picture Flags

V4L2_MPEG2_PIC_FLAG_TOP_FIELD_FIRST	0x00000001	If set and it’s an interlaced stream, top field is output first.
V4L2_MPEG2_PIC_FLAG_FRAME_PRED_DCT	0x00000002	If set only frame-DCT and frame prediction are used.
V4L2_MPEG2_PIC_FLAG_CONCEALMENT_MV	0x00000004	If set motion vectors are coded for intra macroblocks.
V4L2_MPEG2_PIC_FLAG_Q_SCALE_TYPE	0x00000008	This flag affects the inverse quantization process.
V4L2_MPEG2_PIC_FLAG_INTRA_VLC	0x00000010	This flag affects the decoding of transform coefficient data.
V4L2_MPEG2_PIC_FLAG_ALT_SCAN	0x00000020	This flag affects the decoding of transform coefficient data.
V4L2_MPEG2_PIC_FLAG_REPEAT_FIRST	0x00000040	This flag affects the decoding process of progressive frames.
V4L2_MPEG2_PIC_FLAG_PROGRESSIVE	0x00000080	Indicates whether the current frame is progressive.

V4L2_CID_STATELESS_MPEG2_QUANTISATION (struct)

Specifies quantisation matrices, in zigzag scanning order, for the associated MPEG-2 slice data. This control is initialized by the kernel to the matrices default values. If a bitstream transmits a user-defined quantisation matrices load, applications are expected to use this control. Applications are also expected to set the control loading the default values, if the quantisation matrices need to be reset, for instance on a sequence header. This process is specified by section 6.3.7. “Quant matrix extension” of the specification.

type v4l2_ctrl_mpeg2_quantisation

struct v4l2_ctrl_mpeg2_quantisation

__u8	intra_quantiser_matrix[64]	The quantisation matrix coefficients for intra-coded frames, in zigzag scanning order. It is relevant for both luma and chroma components, although it can be superseded by the chroma-specific matrix for non-4:2:0 YUV formats.
__u8	non_intra_quantiser_matrix[64]	The quantisation matrix coefficients for non-intra-coded frames, in zigzag scanning order. It is relevant for both luma and chroma components, although it can be superseded by the chroma-specific matrix for non-4:2:0 YUV formats.
__u8	chroma_intra_quantiser_matrix[64]	The quantisation matrix coefficients for the chominance component of intra-coded frames, in zigzag scanning order. Only relevant for non-4:2:0 YUV formats.
__u8	chroma_non_intra_quantiser_matrix[64]	The quantisation matrix coefficients for the chrominance component of non-intra-coded frames, in zigzag scanning order. Only relevant for non-4:2:0 YUV formats.