From b71901e6ee279f85c06f1ad3ad34b65b8d823a26 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Thu, 19 Sep 2002 17:44:54 +0000 Subject: [PATCH] documenting most stuff in AVCodecContext Originally committed as revision 957 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavcodec/avcodec.h | 437 ++++++++++++++++++++++++++++++++++++------- 1 file changed, 372 insertions(+), 65 deletions(-) diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h index 46cfb4fab9c..2f67329c8df 100644 --- a/libavcodec/avcodec.h +++ b/libavcodec/avcodec.h @@ -105,27 +105,27 @@ static const int Motion_Est_QTab[] = { ME_ZERO, ME_PHODS, ME_LOG, Note: note not everything is supported yet */ -#define CODEC_FLAG_HQ 0x0001 /* high quality (non real time) encoding */ -#define CODEC_FLAG_QSCALE 0x0002 /* use fixed qscale */ -#define CODEC_FLAG_4MV 0x0004 /* 4 MV per MB allowed */ -#define CODEC_FLAG_QPEL 0x0010 /* use qpel MC */ -#define CODEC_FLAG_GMC 0x0020 /* use GMC */ -#define CODEC_FLAG_TYPE 0x0040 /* fixed I/P frame type, from avctx->key_frame */ -#define CODEC_FLAG_PART 0x0080 /* use data partitioning */ +#define CODEC_FLAG_HQ 0x0001 /* brute force MB-type decission mode (slow) */ +#define CODEC_FLAG_QSCALE 0x0002 /* use fixed qscale */ +#define CODEC_FLAG_4MV 0x0004 /* 4 MV per MB allowed */ +#define CODEC_FLAG_QPEL 0x0010 /* use qpel MC */ +#define CODEC_FLAG_GMC 0x0020 /* use GMC */ +#define CODEC_FLAG_TYPE 0x0040 /* fixed I/P frame type, from avctx->key_frame */ +#define CODEC_FLAG_PART 0x0080 /* use data partitioning */ /* parent program gurantees that the input for b-frame containing streams is not written to for at least s->max_b_frames+1 frames, if this is not set than the input will be copied */ #define CODEC_FLAG_INPUT_PRESERVED 0x0100 -#define CODEC_FLAG_PASS1 0x0200 /* use internal 2pass ratecontrol in first pass mode */ -#define CODEC_FLAG_PASS2 0x0400 /* use internal 2pass ratecontrol in second pass mode */ +#define CODEC_FLAG_PASS1 0x0200 /* use internal 2pass ratecontrol in first pass mode */ +#define CODEC_FLAG_PASS2 0x0400 /* use internal 2pass ratecontrol in second pass mode */ #define CODEC_FLAG_EXTERN_HUFF 0x1000 /* use external huffman table (for mjpeg) */ -#define CODEC_FLAG_GRAY 0x2000 /* only decode/encode grayscale */ +#define CODEC_FLAG_GRAY 0x2000 /* only decode/encode grayscale */ #define CODEC_FLAG_EMU_EDGE 0x4000/* dont draw edges */ -#define CODEC_FLAG_DR1 0x8000 /* dr1 */ -#define CODEC_FLAG_NOT_TRUNCATED 0x00010000 /* input bitstream is not truncated, except before a startcode */ +#define CODEC_FLAG_DR1 0x8000 /* direct renderig type 1 (store internal frames in external buffers) */ +#define CODEC_FLAG_NOT_TRUNCATED 0x00010000 /* input bitstream is not truncated, except before a startcode + allows the last part of a frame to be decoded earlier */ /* codec capabilities */ -/* decoder can use draw_horiz_band callback */ -#define CODEC_CAP_DRAW_HORIZ_BAND 0x0001 +#define CODEC_CAP_DRAW_HORIZ_BAND 0x0001 /* decoder can use draw_horiz_band callback */ #define CODEC_CAP_DR1 0x0002 /* direct rendering method 1 */ /* if 'parse_only' field is true, then avcodec_parse_frame() can be used */ @@ -134,23 +134,72 @@ static const int Motion_Est_QTab[] = { ME_ZERO, ME_PHODS, ME_LOG, #define FRAME_RATE_BASE 10000 typedef struct AVCodecContext { + /** + * the average bitrate + * encoding: set by user. unused for constant quantizer encoding + * decoding: set by lavc. 0 or some bitrate if this info is available in the stream + */ int bit_rate; - int bit_rate_tolerance; /* amount of +- bits (>0)*/ + + /** + * number of bits the bitstream is allowed to diverge from the reference + * the reference can be CBR (for CBR pass1) or VBR (for pass2) + * encoding: set by user. unused for constant quantizer encoding + * decoding: unused + */ + int bit_rate_tolerance; + + /** + * CODEC_FLAG_* + * encoding: set by user. + * decoding: set by user. + */ int flags; - int sub_id; /* some codecs needs additionnal format info. It is - stored there */ - - int me_method; /* ME algorithm used for video coding */ - - /* extra data from parent application to codec, e.g. huffman table - for mjpeg */ - /* the parent should allocate and free this buffer */ + + /** + * some codecs needs additionnal format info. It is stored here + * encoding: set by user. + * decoding: set by lavc. (FIXME is this ok?) + */ + int sub_id; + + /** + * motion estimation algorithm used for video coding + * encoding: set by user. + * decoding: unused + */ + int me_method; + + /** + * some codecs need / can use extra-data like huffman tables + * mjpeg: huffman tables + * rv10: additional flags + * encoding: set/allocated/freed by user. + * decoding: set/allocated/freed by lavc. (can be NULL) + */ void *extradata; int extradata_size; /* video only */ - int frame_rate; /* frames per sec multiplied by FRAME_RATE_BASE */ + /** + * frames per sec multiplied by FRAME_RATE_BASE + * for variable fps this is the precission, so if the timestamps + * can be specified in msec precssion then this is 1000*FRAME_RATE_BASE + * encoding: set by user + * decoding: set by lavc. 0 or the frame_rate if available + */ + int frame_rate; + + /** + * encoding: set by user. + * decoding: set by user, some codecs might override / change it during playback + */ int width, height; + + /** + * encoding: set by user. 0 if not known + * decoding: set by lavc. 0 if not known + */ int aspect_ratio_info; #define FF_ASPECT_SQUARE 1 #define FF_ASPECT_4_3_625 2 @@ -158,15 +207,33 @@ typedef struct AVCodecContext { #define FF_ASPECT_16_9_625 4 #define FF_ASPECT_16_9_525 5 #define FF_ASPECT_EXTENDED 15 - int gop_size; /* 0 = intra only */ - enum PixelFormat pix_fmt; /* pixel format, see PIX_FMT_xxx */ + + /** + * the number of pictures in a group of pitures, or 0 for intra_only + * encoding: set by user. + * decoding: unused + */ + int gop_size; + + /** + * pixel format, see PIX_FMT_xxx + * encoding: unused + * decoding: set by lavc. + */ + enum PixelFormat pix_fmt; + int repeat_pict; /* when decoding, this signal how much the picture */ /* must be delayed. */ /* extra_delay = (repeat_pict / 2) * (1/fps) */ - /* if non NULL, 'draw_horiz_band' is called by the libavcodec - decoder to draw an horizontal band. It improve cache usage. Not - all codecs can do that. You must check the codec capabilities - before */ + + /** + * if non NULL, 'draw_horiz_band' is called by the libavcodec + * decoder to draw an horizontal band. It improve cache usage. Not + * all codecs can do that. You must check the codec capabilities + * before + * encoding: unused + * decoding: set by user. + */ void (*draw_horiz_band)(struct AVCodecContext *s, UINT8 **src_ptr, int linesize, int y, int width, int height); @@ -181,20 +248,41 @@ typedef struct AVCodecContext { int frame_number; /* audio or video frame number */ int real_pict_num; /* returns the real picture number of previous encoded frame */ - int key_frame; /* true if the previous compressed frame was - a key frame (intra, or seekable) */ - int pict_type; /* picture type of the previous - en/decoded frame */ + + /** + * 1 -> keyframe, 0-> not + * encoding: set by lavc (for the outputed bitstream, not the input frame) + * decoding: set by lavc (for the decoded bitstream, not the displayed frame) + */ + int key_frame; + + /** + * picture type of the previous en/decoded frame, see ?_TYPE below + * encoding: set by lavc (for the outputed bitstream, not the input frame) + * decoding: set by lavc (for the decoded bitstream, not the displayed frame) + */ + int pict_type; /* FIXME: these should have FF_ */ #define I_TYPE 1 // Intra #define P_TYPE 2 // Predicted #define B_TYPE 3 // Bi-dir predicted #define S_TYPE 4 // S(GMC)-VOP MPEG4 - int delay; /* number of frames the decoded output - will be delayed relative to the encoded input */ - uint8_t *mbskip_table; /* =1 if MB didnt change, is only valid for I/P frames - stride= mb_width = (width+15)>>4 */ + /** + * number of frames the decoded output will be delayed relative to + * the encoded input + * encoding: set by lavc. + * decoding: unused + */ + int delay; + + /** + * mbskip_table[mb]=1 if MB didnt change, is only valid for I/P frames + * stride= mb_width = (width+15)>>4 (FIXME export stride?) + * encoding: unused + * decoding: set by lavc + */ + uint8_t *mbskip_table; /* encoding parameters */ int quality; /* quality of the previous encoded frame @@ -203,18 +291,55 @@ typedef struct AVCodecContext { and the per frame quality in CODEC_FLAG_TYPE (second pass mode) */ float qcompress; /* amount of qscale change between easy & hard scenes (0.0-1.0)*/ float qblur; /* amount of qscale smoothing over time (0.0-1.0) */ - int qmin; /* min qscale */ - int qmax; /* max qscale */ - int max_qdiff; /* max qscale difference between frames */ - int max_b_frames; /* maximum b frames, the output will be delayed by max_b_frames+1 relative to the input */ - float b_quant_factor;/* qscale factor between ps and b frames */ - int rc_strategy; /* obsolete FIXME remove */ + + /** + * minimum quantizer + * encoding: set by user. + * decoding: unused + */ + int qmin; + + /** + * maximum quantizer + * encoding: set by user. + * decoding: unused + */ + int qmax; + + /** + * maximum quantizer difference etween frames + * encoding: set by user. + * decoding: unused + */ + int max_qdiff; + + /** + * maximum number of b frames between non b frames + * note: the output will be delayed by max_b_frames+1 relative to the input + * encoding: set by user. + * decoding: unused + */ + int max_b_frames; + + /** + * qscale factor between ip and b frames + * encoding: set by user. + * decoding: unused + */ + float b_quant_factor; + + /** obsolete FIXME remove */ + int rc_strategy; int b_frame_strategy; - int hurry_up; /* when set to 1 during decoding, b frames will be skiped - when set to 2 idct/dequant will be skipped too */ + /** + * encoding: unused + * decoding: set by user. 1-> skip b frames, 2-> skip idct/dequant too + */ + int hurry_up; struct AVCodec *codec; + void *priv_data; /* The following data is for RTP friendly coding */ @@ -237,8 +362,12 @@ typedef struct AVCodecContext { /* with a Start Code (it should) H.263 does */ void (*rtp_callback)(void *data, int size, int packet_number); - /* These are for PSNR calculation, if you set get_psnr to 1 */ - /* after encoding you will have the PSNR on psnr_y/cb/cr */ + /** + * if you set get_psnr to 1 then after encoding you will have the + * PSNR on psnr_y/cb/cr + * encoding: set by user (1-> on, 0-> off) + * decoding: unused + */ int get_psnr; float psnr_y; float psnr_cb; @@ -252,21 +381,66 @@ typedef struct AVCodecContext { int i_count; int p_count; int skip_count; - int misc_bits; // cbp, mb_type + int misc_bits; + + /** + * number of bits used for the previously encoded frame + * encoding: set by lavc + * decoding: unused + */ int frame_bits; - /* the following fields are ignored */ - void *opaque; /* can be used to carry app specific stuff */ + /** + * private data of the user, can be used to carry app specific stuff + * encoding: set by user + * decoding: set by user + */ + void *opaque; + char codec_name[32]; enum CodecType codec_type; /* see CODEC_TYPE_xxx */ enum CodecID codec_id; /* see CODEC_ID_xxx */ unsigned int codec_tag; /* codec tag, only used if unknown codec */ - int workaround_bugs; /* workaround bugs in encoders which cannot be detected automatically */ + /** + * workaround bugs in encoders which cannot be detected automatically + * encoding: unused + * decoding: set by user + */ + int workaround_bugs; + + /** + * encoding: set by user + * decoding: unused + */ int luma_elim_threshold; + + /** + * encoding: set by user + * decoding: unused + */ int chroma_elim_threshold; - int strict_std_compliance; /* strictly follow the std (MPEG4, ...) */ - float b_quant_offset;/* qscale offset between ips and b frames, not implemented yet */ + + /** + * strictly follow the std (MPEG4, ...) + * encoding: set by user + * decoding: unused + */ + int strict_std_compliance; + + /** + * qscale offset between ip and b frames + * encoding: set by user. + * decoding: unused + */ + float b_quant_offset; + + /** + * error resilience {-1,0,1} higher values will detect more errors but may missdetect + * some more or less valid parts as errors + * encoding: unused + * decoding: set by user + */ int error_resilience; #ifndef MBC @@ -278,41 +452,168 @@ typedef struct AVCodecContext { QP_TYPE *quant_store; /* field for communicating with external postprocessing */ unsigned qstride; + + /** + * buffer, where the next picture should be decoded into + * encoding: unused + * decoding: set by user in get_buffer_callback to a buffer into which the next part + * of the bitstream will be decoded, and set by lavc at end of frame to the + * next frame which needs to be displayed + */ uint8_t *dr_buffer[3]; + + /** + * stride of the luminance part of the dr buffer + * encoding: unused + * decoding: set by user + */ int dr_stride; + + /** + * same behavior as dr_buffer, just for some private data of the user + * encoding: unused + * decoding: set by user in get_buffer_callback, and set by lavc at end of frame + */ void *dr_opaque_frame; + + /** + * called at the beginning of each frame to get a buffer for it + * encoding: unused + * decoding: set by user + */ void (*get_buffer_callback)(struct AVCodecContext *c, int width, int height, int pict_type); - int has_b_frames; // is 1 if the decoded stream contains b frames + /** + * is 1 if the decoded stream contains b frames, 0 otherwise + * encoding: unused + * decoding: set by lavc + */ + int has_b_frames; + + /** + * stride of the chrominance part of the dr buffer + * encoding: unused + * decoding: set by user + */ int dr_uvstride; + + /** + * number of dr buffers + * encoding: unused + * decoding: set by user + */ int dr_ip_buffer_count; + int block_align; /* currently only for adpcm codec in wav/avi */ int parse_only; /* decoding only: if true, only parsing is done (function avcodec_parse_frame()). The frame data is returned. Only MPEG codecs support this now. */ - int mpeg_quant; /* 0-> h263 quant 1-> mpeg quant */ + /** + * 0-> h263 quant 1-> mpeg quant + * encoding: set by user. + * decoding: unused + */ + int mpeg_quant; + /** + * pass1 encoding statistics output buffer + * encoding: set by lavc + * decoding: unused + */ char *stats_out; /* encoding statistics output buffer */ - char *stats_in; /* encoding statistics input buffer (concatenated stuff from stats_out of pass1 should be placed here)*/ + + /** + * pass2 encoding statistics input buffer. + * concatenated stuff from stats_out of pass1 should be placed here + * encoding: allocated/set/freed by user + * decoding: unused + */ + char *stats_in; + + /** + * ratecontrol qmin qmax limiting method + * 0-> clipping, 1-> use a nice continous function to limit qscale wthin qmin/qmax + * encoding: set by user. + * decoding: unused + */ float rc_qsquish; + float rc_qmod_amp; int rc_qmod_freq; + + /** + * ratecontrol override, see RcOverride + * encoding: allocated/set/freed by user. + * decoding: unused + */ RcOverride *rc_override; int rc_override_count; + + /** + * rate control equation + * encoding: set by user + * decoding: unused + */ char *rc_eq; + + /** + * maximum bitrate + * encoding: set by user. + * decoding: unused + */ int rc_max_rate; + + /** + * minimum bitrate + * encoding: set by user. + * decoding: unused + */ int rc_min_rate; + + /** + * decoder bitstream buffer size + * encoding: set by user. + * decoding: unused + */ int rc_buffer_size; float rc_buffer_aggressivity; - float i_quant_factor;/* qscale factor between i and p frames */ - float i_quant_offset;/* qscale offset between i and p frames */ + + /** + * qscale factor between p and i frames + * encoding: set by user. + * decoding: unused + */ + float i_quant_factor; + + /** + * qscale offset between p and i frames + * encoding: set by user. + * decoding: unused + */ + float i_quant_offset; + + /** + * initial complexity for pass1 ratecontrol + * encoding: set by user. + * decoding: unused + */ float rc_initial_cplx; + /** + * custom aspect ratio, used if aspect_info==FF_ASPECT_EXTENDED + * encoding: set by user. + * decoding: set by lavc. + */ int aspected_width; int aspected_height; + /** + * dct algorithm, see FF_DCT_* below + * encoding: set by user + * decoding: unused + */ int dct_algo; #define FF_DCT_AUTO 0 #define FF_DCT_FASTINT 1 @@ -320,10 +621,13 @@ typedef struct AVCodecContext { #define FF_DCT_MMX 3 #define FF_DCT_MLIB 4 - long long int pts; /* timestamp in micro seconds - for decoding: the timestamp from the stream or 0 - for encoding: the timestamp which will be stored in the stream - if 0 then the frame_rate will be used */ + /** + * presentation timestamp in micro seconds (time when frame should be shown to user) + * if 0 then the frame_rate will be used as reference + * encoding: set by user + * decoding; set by lavc + */ + long long int pts; //FIXME this should be reordered after kabis API is finished ... //TODO kill kabi @@ -333,8 +637,11 @@ typedef struct AVCodecContext { If you'll perform some changes then borrow new space from these fields (void * can be safety replaced with struct * ;) P L E A S E ! ! ! - IMPORTANT: Never change order of already declared fields!!! - */ + Note: use avcodec_alloc_context instead of malloc to allocate this, + otherwise the ABI compatibility will be broken between versions + IMPORTANT: Never change order of already declared fields!!! + */ + //TODO: remove mess below unsigned long long int ull_res0,ull_res1,ull_res2,ull_res3,ull_res4,ull_res5, ull_res6,ull_res7,ull_res8,ull_res9,ull_res10,ull_res11; -- 2.39.2