[FFmpeg-devel] [PATCH v2 3/3] avcodec/avs2_parser: parse more info
"zhilizhao(赵志立)"
quinkblack at foxmail.com
Mon Jun 13 06:42:06 EEST 2022
> On Jun 13, 2022, at 1:07 AM, Andreas Rheinhardt <andreas.rheinhardt at outlook.com> wrote:
>
> 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.
Thanks for the review, fixed by v3:
1. Move ff_avs2_frame_rate_tab from avs2.h to avs2.c
2. Consitify `precision` in patch 3/5
3. init_get_bits8() with size limites to buf_size_min
4. Select avs2_parser for libdavs2
5. Use ff_avs2_frame_rate_tab in libdavs2
http://ffmpeg.org/pipermail/ffmpeg-devel/2022-June/297476.html
>
>> + { 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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