ffmpeg/libavcodec/cbs_mpeg2.h

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/*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef AVCODEC_CBS_MPEG2_H
#define AVCODEC_CBS_MPEG2_H
#include <stddef.h>
#include <stdint.h>
#include "libavutil/buffer.h"
enum {
MPEG2_START_PICTURE = 0x00,
MPEG2_START_SLICE_MIN = 0x01,
MPEG2_START_SLICE_MAX = 0xaf,
MPEG2_START_USER_DATA = 0xb2,
MPEG2_START_SEQUENCE_HEADER = 0xb3,
MPEG2_START_SEQUENCE_ERROR = 0xb4,
MPEG2_START_EXTENSION = 0xb5,
MPEG2_START_SEQUENCE_END = 0xb7,
MPEG2_START_GROUP = 0xb8,
};
#define MPEG2_START_IS_SLICE(type) \
((type) >= MPEG2_START_SLICE_MIN && \
(type) <= MPEG2_START_SLICE_MAX)
enum {
MPEG2_EXTENSION_SEQUENCE = 0x1,
MPEG2_EXTENSION_SEQUENCE_DISPLAY = 0x2,
MPEG2_EXTENSION_QUANT_MATRIX = 0x3,
MPEG2_EXTENSION_COPYRIGHT = 0x4,
MPEG2_EXTENSION_SEQUENCE_SCALABLE = 0x5,
MPEG2_EXTENSION_PICTURE_DISPLAY = 0x7,
MPEG2_EXTENSION_PICTURE_CODING = 0x8,
MPEG2_EXTENSION_PICTURE_SPATIAL_SCALABLE = 0x9,
MPEG2_EXTENSION_PICTURE_TEMPORAL_SCALABLE = 0xa,
MPEG2_EXTENSION_CAMERA_PARAMETERS = 0xb,
MPEG2_EXTENSION_ITU_T = 0xc,
};
typedef struct MPEG2RawSequenceHeader {
uint8_t sequence_header_code;
uint16_t horizontal_size_value;
uint16_t vertical_size_value;
uint8_t aspect_ratio_information;
uint8_t frame_rate_code;
uint32_t bit_rate_value;
uint16_t vbv_buffer_size_value;
uint8_t constrained_parameters_flag;
uint8_t load_intra_quantiser_matrix;
uint8_t intra_quantiser_matrix[64];
uint8_t load_non_intra_quantiser_matrix;
uint8_t non_intra_quantiser_matrix[64];
} MPEG2RawSequenceHeader;
typedef struct MPEG2RawUserData {
uint8_t user_data_start_code;
uint8_t *user_data;
AVBufferRef *user_data_ref;
size_t user_data_length;
} MPEG2RawUserData;
typedef struct MPEG2RawSequenceExtension {
uint8_t profile_and_level_indication;
uint8_t progressive_sequence;
uint8_t chroma_format;
uint8_t horizontal_size_extension;
uint8_t vertical_size_extension;
uint16_t bit_rate_extension;
uint8_t vbv_buffer_size_extension;
uint8_t low_delay;
uint8_t frame_rate_extension_n;
uint8_t frame_rate_extension_d;
} MPEG2RawSequenceExtension;
typedef struct MPEG2RawSequenceDisplayExtension {
uint8_t video_format;
uint8_t colour_description;
uint8_t colour_primaries;
uint8_t transfer_characteristics;
uint8_t matrix_coefficients;
uint16_t display_horizontal_size;
uint16_t display_vertical_size;
} MPEG2RawSequenceDisplayExtension;
typedef struct MPEG2RawGroupOfPicturesHeader {
uint8_t group_start_code;
uint32_t time_code;
uint8_t closed_gop;
uint8_t broken_link;
} MPEG2RawGroupOfPicturesHeader;
cbs_mpeg2: Fix parsing of picture and slice headers 1. The extra information in slice headers was parsed incorrectly: In the first reading pass to derive the length of the extra information, one should look at bits n, n + 9, n + 18, ... and check whether they equal one (further extra information) or zero (end of extra information), but instead bits n, n + 8, n + 16, ... were inspected. The second pass of reading (where the length is already known and the bytes between the length-determining bits are copied into a buffer) did not record what was in bits n, n + 9, n + 18, ..., presuming they equal one. And during writing, the bytes in the buffer are interleaved with set bits and written. This means that if the detected length of the extra information was greater than the real length, the output was corrupted. Fortunately no sample is known that made use of this mechanism: The extra information in slices is still marked as reserved in the specifications. cbs_mpeg2 is now ready in case this changes. 2. Furthermore, the buffer is now padded and slightly different, but very similar code for reading resp. writing has been replaced by code used for both. This was made possible by a new macro, the equivalent to cbs_h2645's fixed(). 3. These changes also made it possible to remove the extra_bit_slice element from the MPEG2RawSliceHeader structure. Said element was always zero except when the detected length of the extra information was less than the real length. 4. The extra information in picture headers (which uses essentially the same syntax as the extra information in slice headers) has simply been forgotten. This meant that if this extra information was present, it was discarded during reading; and unfortunately writing created invalid bitstreams in this case (an extra_bit_picture - the last set bit of the whole unit - indicated that there would be a further byte of data, although the output didn't contain said data). This has been fixed; both types of extra information are now parsed via the same code and essentially passed through. Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
2019-06-19 23:45:12 +00:00
typedef struct MPEG2RawExtraInformation {
uint8_t *extra_information;
AVBufferRef *extra_information_ref;
size_t extra_information_length;
} MPEG2RawExtraInformation;
typedef struct MPEG2RawPictureHeader {
uint8_t picture_start_code;
uint16_t temporal_reference;
uint8_t picture_coding_type;
uint16_t vbv_delay;
uint8_t full_pel_forward_vector;
uint8_t forward_f_code;
uint8_t full_pel_backward_vector;
uint8_t backward_f_code;
cbs_mpeg2: Fix parsing of picture and slice headers 1. The extra information in slice headers was parsed incorrectly: In the first reading pass to derive the length of the extra information, one should look at bits n, n + 9, n + 18, ... and check whether they equal one (further extra information) or zero (end of extra information), but instead bits n, n + 8, n + 16, ... were inspected. The second pass of reading (where the length is already known and the bytes between the length-determining bits are copied into a buffer) did not record what was in bits n, n + 9, n + 18, ..., presuming they equal one. And during writing, the bytes in the buffer are interleaved with set bits and written. This means that if the detected length of the extra information was greater than the real length, the output was corrupted. Fortunately no sample is known that made use of this mechanism: The extra information in slices is still marked as reserved in the specifications. cbs_mpeg2 is now ready in case this changes. 2. Furthermore, the buffer is now padded and slightly different, but very similar code for reading resp. writing has been replaced by code used for both. This was made possible by a new macro, the equivalent to cbs_h2645's fixed(). 3. These changes also made it possible to remove the extra_bit_slice element from the MPEG2RawSliceHeader structure. Said element was always zero except when the detected length of the extra information was less than the real length. 4. The extra information in picture headers (which uses essentially the same syntax as the extra information in slice headers) has simply been forgotten. This meant that if this extra information was present, it was discarded during reading; and unfortunately writing created invalid bitstreams in this case (an extra_bit_picture - the last set bit of the whole unit - indicated that there would be a further byte of data, although the output didn't contain said data). This has been fixed; both types of extra information are now parsed via the same code and essentially passed through. Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
2019-06-19 23:45:12 +00:00
MPEG2RawExtraInformation extra_information_picture;
} MPEG2RawPictureHeader;
typedef struct MPEG2RawPictureCodingExtension {
uint8_t f_code[2][2];
uint8_t intra_dc_precision;
uint8_t picture_structure;
uint8_t top_field_first;
uint8_t frame_pred_frame_dct;
uint8_t concealment_motion_vectors;
uint8_t q_scale_type;
uint8_t intra_vlc_format;
uint8_t alternate_scan;
uint8_t repeat_first_field;
uint8_t chroma_420_type;
uint8_t progressive_frame;
uint8_t composite_display_flag;
uint8_t v_axis;
uint8_t field_sequence;
uint8_t sub_carrier;
uint8_t burst_amplitude;
uint8_t sub_carrier_phase;
} MPEG2RawPictureCodingExtension;
typedef struct MPEG2RawQuantMatrixExtension {
uint8_t load_intra_quantiser_matrix;
uint8_t intra_quantiser_matrix[64];
uint8_t load_non_intra_quantiser_matrix;
uint8_t non_intra_quantiser_matrix[64];
uint8_t load_chroma_intra_quantiser_matrix;
uint8_t chroma_intra_quantiser_matrix[64];
uint8_t load_chroma_non_intra_quantiser_matrix;
uint8_t chroma_non_intra_quantiser_matrix[64];
} MPEG2RawQuantMatrixExtension;
typedef struct MPEG2RawPictureDisplayExtension {
int16_t frame_centre_horizontal_offset[3];
int16_t frame_centre_vertical_offset[3];
} MPEG2RawPictureDisplayExtension;
typedef struct MPEG2RawExtensionData {
uint8_t extension_start_code;
uint8_t extension_start_code_identifier;
union {
MPEG2RawSequenceExtension sequence;
MPEG2RawSequenceDisplayExtension sequence_display;
MPEG2RawQuantMatrixExtension quant_matrix;
MPEG2RawPictureCodingExtension picture_coding;
MPEG2RawPictureDisplayExtension picture_display;
} data;
} MPEG2RawExtensionData;
typedef struct MPEG2RawSliceHeader {
uint8_t slice_vertical_position;
uint8_t slice_vertical_position_extension;
uint8_t priority_breakpoint;
uint8_t quantiser_scale_code;
uint8_t slice_extension_flag;
uint8_t intra_slice;
uint8_t slice_picture_id_enable;
uint8_t slice_picture_id;
cbs_mpeg2: Fix parsing of picture and slice headers 1. The extra information in slice headers was parsed incorrectly: In the first reading pass to derive the length of the extra information, one should look at bits n, n + 9, n + 18, ... and check whether they equal one (further extra information) or zero (end of extra information), but instead bits n, n + 8, n + 16, ... were inspected. The second pass of reading (where the length is already known and the bytes between the length-determining bits are copied into a buffer) did not record what was in bits n, n + 9, n + 18, ..., presuming they equal one. And during writing, the bytes in the buffer are interleaved with set bits and written. This means that if the detected length of the extra information was greater than the real length, the output was corrupted. Fortunately no sample is known that made use of this mechanism: The extra information in slices is still marked as reserved in the specifications. cbs_mpeg2 is now ready in case this changes. 2. Furthermore, the buffer is now padded and slightly different, but very similar code for reading resp. writing has been replaced by code used for both. This was made possible by a new macro, the equivalent to cbs_h2645's fixed(). 3. These changes also made it possible to remove the extra_bit_slice element from the MPEG2RawSliceHeader structure. Said element was always zero except when the detected length of the extra information was less than the real length. 4. The extra information in picture headers (which uses essentially the same syntax as the extra information in slice headers) has simply been forgotten. This meant that if this extra information was present, it was discarded during reading; and unfortunately writing created invalid bitstreams in this case (an extra_bit_picture - the last set bit of the whole unit - indicated that there would be a further byte of data, although the output didn't contain said data). This has been fixed; both types of extra information are now parsed via the same code and essentially passed through. Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
2019-06-19 23:45:12 +00:00
MPEG2RawExtraInformation extra_information_slice;
} MPEG2RawSliceHeader;
typedef struct MPEG2RawSlice {
MPEG2RawSliceHeader header;
uint8_t *data;
AVBufferRef *data_ref;
size_t data_size;
int data_bit_start;
} MPEG2RawSlice;
typedef struct MPEG2RawSequenceEnd {
uint8_t sequence_end_code;
} MPEG2RawSequenceEnd;
typedef struct CodedBitstreamMPEG2Context {
// Elements stored in headers which are required for other decoding.
uint16_t horizontal_size;
uint16_t vertical_size;
uint8_t scalable;
uint8_t scalable_mode;
uint8_t progressive_sequence;
uint8_t number_of_frame_centre_offsets;
} CodedBitstreamMPEG2Context;
#endif /* AVCODEC_CBS_MPEG2_H */