Re: [FFmpeg-devel] [PATCH v3 3/5] avcodec/avs2_parser: parse more info

["\"zhilizhao(赵志立)\"" <quinkblack@foxmail.com>]

> On Jun 21, 2022, at 10:45 AM, hwren <hwrenx@126.com> wrote:
> 
> At 2022-06-13 11:36:34, "Zhao Zhili" <quinkblack@foxmail.com> wrote:
>> Including video resolution, framerate and picture type, etc.
>> 
>> Signed-off-by: Zhao Zhili <zhilizhao@tencent.com>
>> ---
>> libavcodec/Makefile      |   2 +-
>> libavcodec/avs2.c        |  42 ++++++++++++++++
>> libavcodec/avs2.h        |  10 ++++
>> libavcodec/avs2_parser.c | 105 +++++++++++++++++++++++++++++++++++++++
>> 4 files changed, 158 insertions(+), 1 deletion(-)
>> create mode 100644 libavcodec/avs2.c
>> 
>> diff --git a/libavcodec/Makefile b/libavcodec/Makefile
>> index 3b8f7b5e01..6cc6f8437c 100644
>> --- a/libavcodec/Makefile
>> +++ b/libavcodec/Makefile
>> @@ -1114,7 +1114,7 @@ OBJS-$(CONFIG_AC3_PARSER)              += aac_ac3_parser.o ac3tab.o \
>> OBJS-$(CONFIG_ADX_PARSER)              += adx_parser.o adx.o
>> OBJS-$(CONFIG_AMR_PARSER)              += amr_parser.o
>> OBJS-$(CONFIG_AV1_PARSER)              += av1_parser.o
>> -OBJS-$(CONFIG_AVS2_PARSER)             += avs2_parser.o
>> +OBJS-$(CONFIG_AVS2_PARSER)             += avs2.o avs2_parser.o
>> OBJS-$(CONFIG_AVS3_PARSER)             += avs3_parser.o
>> OBJS-$(CONFIG_BMP_PARSER)              += bmp_parser.o
>> OBJS-$(CONFIG_CAVSVIDEO_PARSER)        += cavs_parser.o
>> diff --git a/libavcodec/avs2.c b/libavcodec/avs2.c
>> new file mode 100644
>> index 0000000000..ead8687d0a
>> --- /dev/null
>> +++ b/libavcodec/avs2.c
>> @@ -0,0 +1,42 @@
>> +/*
>> + * AVS2 related definitions
>> + *
>> + * Copyright (C) 2022 Zhao Zhili, <zhilizhao@tencent.com>
>> + *
>> + * 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
>> + */
>> +
>> +#include "avs2.h"
>> +
>> +const AVRational ff_avs2_frame_rate_tab[16] = {
>> +    { 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
>> +};
> 
> That table seems to appear only in avs2 decoder. If so, they are supposed to be declared in libdavs2.c.
> If not, please point out the usage of this separate source file.

It’s used in this patch, parse_avs2_seq_header().

> 
> Persionally, the frame_rate table can be used in both encoder and decoder. So it is what should be
> defined in the avs2.h (with related enc/dec changes).

It’s declared in avs2.h, so it can be used by enc/dec.
It’s defined in .c to reduce binary size.

> 
>> diff --git a/libavcodec/avs2.h b/libavcodec/avs2.h
>> index f342ba52a0..544cf502d7 100644
>> --- a/libavcodec/avs2.h
>> +++ b/libavcodec/avs2.h
>> @@ -23,6 +23,8 @@
>> #ifndef AVCODEC_AVS2_H
>> #define AVCODEC_AVS2_H
>> 
>> +#include "libavutil/rational.h"
>> +
>> #define AVS2_SLICE_MAX_START_CODE    0x000001AF
>> 
>> enum {
>> @@ -38,4 +40,12 @@ 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))
>> 
> 
> Same as above. Mentioned definitions now are only used in avs2_parser.c. If so, they are supposed to be
> kept in avs2_parser.c.

It’s not the same as ff_avs2_frame_rate_tab. Firstly, define enum
and macros doesn’t generate binary. Secondly, they are be used
by avs2 parser/decoder/encoder and so on, the same as avs3.h.

They are only used by avs2 parser now, but they are handy when debug
decoder, for example, and future proof.

> 
> 
>> +enum AVS2Profile {
>> +    AVS2_PROFILE_MAIN_PIC   = 0x12,
>> +    AVS2_PROFILE_MAIN       = 0x20,
>> +    AVS2_PROFILE_MAIN10     = 0x22,
>> +};
> 
> Not mentioned elsewhere. If they are to work in the encoder/decoder, please package them with related changes.

AVS2_PROFILE_MAIN10 is used in this patch.

> 
>> +
>> +extern const AVRational ff_avs2_frame_rate_tab[16];
>> +
>> #endif
>> diff --git a/libavcodec/avs2_parser.c b/libavcodec/avs2_parser.c
>> index 71cf442903..0350517493 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 +60,107 @@ 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 const uint8_t precision[8] = { 0, 8, 10 };
>> +    unsigned aspect_ratio;
>> +    unsigned frame_rate_code;
>> +    int low_delay;
>> +    // update buf_size_min if parse more deeper
>> +    const int buf_size_min = 15;
>> +
>> +    if (buf_size < buf_size_min)
>> +        return;
>> +
>> +    init_get_bits8(&gb, buf, buf_size_min);
>> +
>> +    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 +179,8 @@ static int avs2_parse(AVCodecParserContext *s, AVCodecContext *avctx,
>>        }
>>    }
>> 
>> +    parse_avs2_units(s, buf, buf_size, avctx);
>> +
>>    *poutbuf = buf;
>>    *poutbuf_size = buf_size;
>> 
>> -- 
>> 2.35.3
> 
> 
> Best Regards,
> Huiwen Ren
> 
>> 
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> 
> 
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