[FFmpeg-devel] [PATCH v2 3/3] avcodec/avs2_parser: parse more info
Andreas Rheinhardt
andreas.rheinhardt at outlook.com
Sun Jun 12 20:07:17 EEST 2022
Zhao Zhili:
> Including video resolution, framerate and picture type, etc.
>
> Signed-off-by: Zhao Zhili <quinkblack at foxmail.com>
> ---
> v2: fix unused variable warning
>
> libavcodec/avs2.h | 27 ++++++++++
> libavcodec/avs2_parser.c | 103 +++++++++++++++++++++++++++++++++++++++
> 2 files changed, 130 insertions(+)
>
> diff --git a/libavcodec/avs2.h b/libavcodec/avs2.h
> index f342ba52a0..e961c7d517 100644
> --- a/libavcodec/avs2.h
> +++ b/libavcodec/avs2.h
> @@ -23,6 +23,8 @@
> #ifndef AVCODEC_AVS2_H
> #define AVCODEC_AVS2_Hto
>
> +#include "libavutil/rational.h"
> +
> #define AVS2_SLICE_MAX_START_CODE 0x000001AF
>
> enum {
> @@ -38,4 +40,29 @@ enum {
> #define AVS2_ISPIC(x) ((x) == AVS2_INTRA_PIC_START_CODE || (x) == AVS2_INTER_PIC_START_CODE)
> #define AVS2_ISUNIT(x) ((x) == AVS2_SEQ_START_CODE || AVS2_ISPIC(x))
>
> +enum AVS2Profile {
> + AVS2_PROFILE_MAIN_PIC = 0x12,
> + AVS2_PROFILE_MAIN = 0x20,
> + AVS2_PROFILE_MAIN10 = 0x22,
> +};
> +
> +static const AVRational ff_avs2_frame_rate_tab[16] = {
If this is only used at one place (as it is), it should be moved to that
place; if it is to be used in several places, it should be moved to a
single file instead of a header.
> + { 0 , 0 }, // forbid
> + { 24000, 1001},
> + { 24 , 1 },
> + { 25 , 1 },
> + { 30000, 1001},
> + { 30 , 1 },
> + { 50 , 1 },
> + { 60000, 1001},
> + { 60 , 1 },
> + { 100 , 1 },
> + { 120 , 1 },
> + { 200 , 1 },
> + { 240 , 1 },
> + { 300 , 1 },
> + { 0 , 0 }, // reserved
> + { 0 , 0 } // reserved
> +};
> +
> #endif
> diff --git a/libavcodec/avs2_parser.c b/libavcodec/avs2_parser.c
> index 71cf442903..18d7729768 100644
> --- a/libavcodec/avs2_parser.c
> +++ b/libavcodec/avs2_parser.c
> @@ -19,7 +19,9 @@
> * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
> */
>
> +#include "libavutil/avutil.h"
> #include "avs2.h"
> +#include "get_bits.h"
> #include "parser.h"
>
> static int avs2_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
> @@ -58,6 +60,105 @@ static int avs2_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_siz
> return END_NOT_FOUND;
> }
>
> +static void parse_avs2_seq_header(AVCodecParserContext *s, const uint8_t *buf,
> + int buf_size, AVCodecContext *avctx)
> +{
> + GetBitContext gb;
> + int profile, level;
> + int width, height;
> + int chroma, sample_precision, encoding_precision = 1;
> + // sample_precision and encoding_precision is 3 bits
> + static uint8_t precision[8] = { 0, 8, 10 };
Missing const.
> + unsigned aspect_ratio;
> + unsigned frame_rate_code;
> + int low_delay;
> +
> + if (buf_size < 15)
> + return;
> +
> + init_get_bits8(&gb, buf, buf_size);
If buf_size is gigantic, init_get_bits8 can fail. Given that you only
ever read the first 15 bytes of the header, you can avoid this by
initializing the GetBitContext with a size of 15.
> +
> + s->key_frame = 1;
> + s->pict_type = AV_PICTURE_TYPE_I;
> +
> + profile = get_bits(&gb, 8);
> + level = get_bits(&gb, 8);
> +
> + // progressive_sequence u(1)
> + // field_coded_sequence u(1)
> + skip_bits(&gb, 2);
> +
> + width = get_bits(&gb, 14);
> + height = get_bits(&gb, 14);
> +
> + chroma = get_bits(&gb, 2);
> + sample_precision = get_bits(&gb, 3);
> + if (profile == AVS2_PROFILE_MAIN10)
> + encoding_precision = get_bits(&gb, 3);
> +
> + aspect_ratio = get_bits(&gb, 4);
> + frame_rate_code = get_bits(&gb, 4);
> +
> + // bit_rate_lower u(18)
> + // marker_bit f(1)
> + // bit_rate_upper u(12)
> + skip_bits(&gb, 31);
> +
> + low_delay = get_bits(&gb, 1);
> +
> + s->width = width;
> + s->height = height;
> + s->coded_width = FFALIGN(width, 8);
> + s->coded_height = FFALIGN(height, 8);
> + avctx->framerate.num = avctx->time_base.den =
> + ff_avs2_frame_rate_tab[frame_rate_code].num;
> + avctx->framerate.den = avctx->time_base.num =
> + ff_avs2_frame_rate_tab[frame_rate_code].den;
> + avctx->has_b_frames = FFMAX(avctx->has_b_frames, !low_delay);
> +
> + av_log(avctx, AV_LOG_DEBUG,
> + "AVS2 parse seq HDR: profile %x, level %x, "
> + "width %d, height %d, "
> + "chroma %d, sample_precision %d bits, encoding_precision %d bits, "
> + "aspect_ratio 0x%x, framerate %d/%d, low_delay %d\n",
> + profile, level,
> + width, height,
> + chroma, precision[sample_precision], precision[encoding_precision],
> + aspect_ratio, avctx->framerate.num, avctx->framerate.den, low_delay);
> +}
> +
> +static void parse_avs2_units(AVCodecParserContext *s, const uint8_t *buf,
> + int buf_size, AVCodecContext *avctx)
> +{
> + if (buf_size < 5)
> + return;
> +
> + if (!(buf[0] == 0x0 && buf[1] == 0x0 && buf[2] == 0x1))
> + return;
> +
> + switch (buf[3]) {
> + case AVS2_SEQ_START_CODE:
> + parse_avs2_seq_header(s, buf + 4, buf_size - 4, avctx);
> + return;
> + case AVS2_INTRA_PIC_START_CODE:
> + s->key_frame = 1;
> + s->pict_type = AV_PICTURE_TYPE_I;
> + return;
> + case AVS2_INTER_PIC_START_CODE:
> + s->key_frame = 0;
> + if (buf_size > 9) {
> + int pic_code_type = buf[8] & 0x3;
> + if (pic_code_type == 1)
> + s->pict_type = AV_PICTURE_TYPE_P;
> + else if (pic_code_type == 3)
> + s->pict_type = AV_PICTURE_TYPE_S;
> + else
> + s->pict_type = AV_PICTURE_TYPE_B;
> + }
> + return;
> + }
> +}
> +
> static int avs2_parse(AVCodecParserContext *s, AVCodecContext *avctx,
> const uint8_t **poutbuf, int *poutbuf_size,
> const uint8_t *buf, int buf_size)
> @@ -76,6 +177,8 @@ static int avs2_parse(AVCodecParserContext *s, AVCodecContext *avctx,
> }
> }
>
> + parse_avs2_units(s, buf, buf_size, avctx);
> +
> *poutbuf = buf;
> *poutbuf_size = buf_size;
>
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