From 43da682c87b47eb1880102e0922f64d7abc0dcd5 Mon Sep 17 00:00:00 2001 From: Jordi Ortiz Date: Wed, 22 Aug 2012 13:24:34 +0200 Subject: [PATCH] dirac: add Comments and references to the standard Signed-off-by: Diego Biurrun --- libavcodec/dirac.c | 80 +++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 61 insertions(+), 19 deletions(-) diff --git a/libavcodec/dirac.c b/libavcodec/dirac.c index 3b5d177..489b1f5 100644 --- a/libavcodec/dirac.c +++ b/libavcodec/dirac.c @@ -58,6 +58,7 @@ static const dirac_source_params dirac_source_parameters_defaults[] = { { 7680, 4320, 1, 0, 1, 6, 1, 3840, 2160, 0, 0, 3, 3 }, }; +/* [DIRAC_STD] Table 10.4 - Available preset pixel aspect ratio values */ static const AVRational dirac_preset_aspect_ratios[] = { {1, 1}, {10, 11}, @@ -67,11 +68,16 @@ static const AVRational dirac_preset_aspect_ratios[] = { {4, 3}, }; +/* [DIRAC_STD] Values 9,10 of 10.3.5 Frame Rate. + * Table 10.3 Available preset frame rate values + */ static const AVRational dirac_frame_rate[] = { {15000, 1001}, {25, 2}, }; +/* [DIRAC_STD] This should be equivalent to Table 10.5 Available signal + * range presets */ static const struct { uint8_t bitdepth; enum AVColorRange color_range; @@ -100,11 +106,14 @@ static const struct { { AVCOL_PRI_BT709, AVCOL_SPC_BT709, AVCOL_TRC_UNSPECIFIED /* DCinema */ }, }; +/* [DIRAC_STD] Table 10.2 Supported chroma sampling formats + luma Offset */ static const enum PixelFormat dirac_pix_fmt[2][3] = { { PIX_FMT_YUV444P, PIX_FMT_YUV422P, PIX_FMT_YUV420P }, { PIX_FMT_YUVJ444P, PIX_FMT_YUVJ422P, PIX_FMT_YUVJ420P }, }; +/* [DIRAC_STD] 10.3 Parse Source Parameters. + * source_parameters(base_video_format) */ static int parse_source_parameters(AVCodecContext *avctx, GetBitContext *gb, dirac_source_params *source) { @@ -112,13 +121,18 @@ static int parse_source_parameters(AVCodecContext *avctx, GetBitContext *gb, unsigned luma_depth = 8, luma_offset = 16; int idx; + /* [DIRAC_STD] 10.3.2 Frame size. frame_size(video_params) */ + /* [DIRAC_STD] custom_dimensions_flag */ if (get_bits1(gb)) { - source->width = svq3_get_ue_golomb(gb); - source->height = svq3_get_ue_golomb(gb); + source->width = svq3_get_ue_golomb(gb); /* [DIRAC_STD] FRAME_WIDTH */ + source->height = svq3_get_ue_golomb(gb); /* [DIRAC_STD] FRAME_HEIGHT */ } - // chroma subsampling + /* [DIRAC_STD] 10.3.3 Chroma Sampling Format. + * chroma_sampling_format(video_params) */ + /* [DIRAC_STD] custom_chroma_format_flag */ if (get_bits1(gb)) + /* [DIRAC_STD] CHROMA_FORMAT_INDEX */ source->chroma_format = svq3_get_ue_golomb(gb); if (source->chroma_format > 2) { av_log(avctx, AV_LOG_ERROR, "Unknown chroma format %d\n", @@ -126,34 +140,43 @@ static int parse_source_parameters(AVCodecContext *avctx, GetBitContext *gb, return AVERROR_INVALIDDATA; } + /* [DIRAC_STD] 10.3.4 Scan Format. scan_format(video_params) */ + /* [DIRAC_STD] custom_scan_format_flag */ if (get_bits1(gb)) + /* [DIRAC_STD] SOURCE_SAMPLING */ source->interlaced = svq3_get_ue_golomb(gb); if (source->interlaced > 1) return AVERROR_INVALIDDATA; - // frame rate - if (get_bits1(gb)) { + /* [DIRAC_STD] 10.3.5 Frame Rate. frame_rate(video_params) */ + if (get_bits1(gb)) { /* [DIRAC_STD] custom_frame_rate_flag */ source->frame_rate_index = svq3_get_ue_golomb(gb); if (source->frame_rate_index > 10) return AVERROR_INVALIDDATA; if (!source->frame_rate_index) { + /* [DIRAC_STD] FRAME_RATE_NUMER */ frame_rate.num = svq3_get_ue_golomb(gb); + /* [DIRAC_STD] FRAME_RATE_DENOM */ frame_rate.den = svq3_get_ue_golomb(gb); } } + /* [DIRAC_STD] preset_frame_rate(video_params, index) */ if (source->frame_rate_index > 0) { if (source->frame_rate_index <= 8) frame_rate = avpriv_frame_rate_tab[source->frame_rate_index]; else + /* [DIRAC_STD] Table 10.3 values 9-10 */ frame_rate = dirac_frame_rate[source->frame_rate_index-9]; } av_reduce(&avctx->time_base.num, &avctx->time_base.den, frame_rate.den, frame_rate.num, 1<<30); - // aspect ratio - if (get_bits1(gb)) { + /* [DIRAC_STD] 10.3.6 Pixel Aspect Ratio. + * pixel_aspect_ratio(video_params) */ + if (get_bits1(gb)) { /* [DIRAC_STD] custom_pixel_aspect_ratio_flag */ + /* [DIRAC_STD] index */ source->aspect_ratio_index = svq3_get_ue_golomb(gb); if (source->aspect_ratio_index > 6) @@ -164,19 +187,29 @@ static int parse_source_parameters(AVCodecContext *avctx, GetBitContext *gb, avctx->sample_aspect_ratio.den = svq3_get_ue_golomb(gb); } } + /* [DIRAC_STD] Take value from Table 10.4 Available preset pixel + * aspect ratio values */ if (source->aspect_ratio_index > 0) avctx->sample_aspect_ratio = dirac_preset_aspect_ratios[source->aspect_ratio_index-1]; - if (get_bits1(gb)) { + /* [DIRAC_STD] 10.3.7 Clean area. clean_area(video_params) */ + if (get_bits1(gb)) { /* [DIRAC_STD] custom_clean_area_flag */ + /* [DIRAC_STD] CLEAN_WIDTH */ source->clean_width = svq3_get_ue_golomb(gb); + /* [DIRAC_STD] CLEAN_HEIGHT */ source->clean_height = svq3_get_ue_golomb(gb); + /* [DIRAC_STD] CLEAN_LEFT_OFFSET */ source->clean_left_offset = svq3_get_ue_golomb(gb); + /* [DIRAC_STD] CLEAN_RIGHT_OFFSET */ source->clean_right_offset = svq3_get_ue_golomb(gb); } - // Override signal range. - if (get_bits1(gb)) { + /* [DIRAC_STD] 10.3.8 Signal range. signal_range(video_params) + * WARNING: Some adaptation seems to be done using the + * AVCOL_RANGE_MPEG/JPEG values */ + if (get_bits1(gb)) { /* [DIRAC_STD] custom_signal_range_flag */ + /* [DIRAC_STD] index */ source->pixel_range_index = svq3_get_ue_golomb(gb); if (source->pixel_range_index > 4) @@ -186,12 +219,13 @@ static int parse_source_parameters(AVCodecContext *avctx, GetBitContext *gb, if (!source->pixel_range_index) { luma_offset = svq3_get_ue_golomb(gb); luma_depth = av_log2(svq3_get_ue_golomb(gb))+1; - svq3_get_ue_golomb(gb); // chroma offset - svq3_get_ue_golomb(gb); // chroma excursion - + svq3_get_ue_golomb(gb); /* chroma offset */ + svq3_get_ue_golomb(gb); /* chroma excursion */ avctx->color_range = luma_offset ? AVCOL_RANGE_MPEG : AVCOL_RANGE_JPEG; } } + /* [DIRAC_STD] Table 10.5 + * Available signal range presets <--> pixel_range_presets */ if (source->pixel_range_index > 0) { idx = source->pixel_range_index-1; luma_depth = pixel_range_presets[idx].bitdepth; @@ -203,8 +237,9 @@ static int parse_source_parameters(AVCodecContext *avctx, GetBitContext *gb, avctx->pix_fmt = dirac_pix_fmt[!luma_offset][source->chroma_format]; - // color spec - if (get_bits1(gb)) { + /* [DIRAC_STD] 10.3.9 Colour specification. colour_spec(video_params) */ + if (get_bits1(gb)) { /* [DIRAC_STD] custom_colour_spec_flag */ + /* [DIRAC_STD] index */ idx = source->color_spec_index = svq3_get_ue_golomb(gb); if (source->color_spec_index > 4) @@ -215,12 +250,13 @@ static int parse_source_parameters(AVCodecContext *avctx, GetBitContext *gb, avctx->color_trc = dirac_color_presets[idx].color_trc; if (!source->color_spec_index) { + /* [DIRAC_STD] 10.3.9.1 Colour primaries */ if (get_bits1(gb)) { idx = svq3_get_ue_golomb(gb); if (idx < 3) avctx->color_primaries = dirac_primaries[idx]; } - + /* [DIRAC_STD] 10.3.9.2 Colour matrix */ if (get_bits1(gb)) { idx = svq3_get_ue_golomb(gb); if (!idx) @@ -228,7 +264,7 @@ static int parse_source_parameters(AVCodecContext *avctx, GetBitContext *gb, else if (idx == 1) avctx->colorspace = AVCOL_SPC_BT470BG; } - + /* [DIRAC_STD] 10.3.9.3 Transfer function */ if (get_bits1(gb) && !svq3_get_ue_golomb(gb)) avctx->color_trc = AVCOL_TRC_BT709; } @@ -242,6 +278,7 @@ static int parse_source_parameters(AVCodecContext *avctx, GetBitContext *gb, return 0; } +/* [DIRAC_STD] 10. Sequence Header. sequence_header() */ int avpriv_dirac_parse_sequence_header(AVCodecContext *avctx, GetBitContext *gb, dirac_source_params *source) { @@ -249,10 +286,13 @@ int avpriv_dirac_parse_sequence_header(AVCodecContext *avctx, GetBitContext *gb, unsigned video_format, picture_coding_mode; int ret; + /* [DIRAC_SPEC] 10.1 Parse Parameters. parse_parameters() */ version_major = svq3_get_ue_golomb(gb); svq3_get_ue_golomb(gb); /* version_minor */ avctx->profile = svq3_get_ue_golomb(gb); avctx->level = svq3_get_ue_golomb(gb); + /* [DIRAC_SPEC] sequence_header() -> base_video_format as defined in + * 10.2 Base Video Format, table 10.1 Dirac predefined video formats */ video_format = svq3_get_ue_golomb(gb); if (version_major < 2) @@ -266,7 +306,8 @@ int avpriv_dirac_parse_sequence_header(AVCodecContext *avctx, GetBitContext *gb, // Fill in defaults for the source parameters. *source = dirac_source_parameters_defaults[video_format]; - // Override the defaults. + /* [DIRAC_STD] 10.3 Source Parameters + * Override the defaults. */ if (ret = parse_source_parameters(avctx, gb, source)) return ret; @@ -275,7 +316,8 @@ int avpriv_dirac_parse_sequence_header(AVCodecContext *avctx, GetBitContext *gb, avcodec_set_dimensions(avctx, source->width, source->height); - // currently only used to signal field coding + /* [DIRAC_STD] picture_coding_mode shall be 0 for fields and 1 for frames + * currently only used to signal field coding */ picture_coding_mode = svq3_get_ue_golomb(gb); if (picture_coding_mode != 0) { av_log(avctx, AV_LOG_ERROR, "Unsupported picture coding mode %d", -- 2.7.4