Re: [FFmpeg-devel] [PATCH v3 1/2] lavc: add prores bitstream parser

[Paul B Mahol <onemda@gmail.com>]

On Wed, Jul 26, 2023 at 11:27 AM hung kuishing <hungkuishing@outlook.com>
wrote:

> Signed-off-by: clarkh <hungkuishing@outlook.com>
> ---
>  libavcodec/Makefile        |   1 +
>  libavcodec/parsers.c       |   1 +
>  libavcodec/prores_parser.c | 107 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 109 insertions(+)
>  create mode 100644 libavcodec/prores_parser.c
>

What is usage for this?
Which streams/files need this?

Have parser be tested rigorously with random noise data?


>
> diff --git a/libavcodec/Makefile b/libavcodec/Makefile
> index 1b0226c089..21cd28c9ac 100644
> --- a/libavcodec/Makefile
> +++ b/libavcodec/Makefile
> @@ -1198,6 +1198,7 @@ OBJS-$(CONFIG_OPUS_PARSER)             +=
> opus_parser.o opus_parse.o \
>                                            vorbis_data.o
>  OBJS-$(CONFIG_PNG_PARSER)              += png_parser.o
>  OBJS-$(CONFIG_PNM_PARSER)              += pnm_parser.o pnm.o
> +OBJS-$(CONFIG_PRORES_PARSER)           += prores_parser.o
>  OBJS-$(CONFIG_QOI_PARSER)              += qoi_parser.o
>  OBJS-$(CONFIG_RV30_PARSER)             += rv34_parser.o
>  OBJS-$(CONFIG_RV40_PARSER)             += rv34_parser.o
> diff --git a/libavcodec/parsers.c b/libavcodec/parsers.c
> index 285f81a901..131867686a 100644
> --- a/libavcodec/parsers.c
> +++ b/libavcodec/parsers.c
> @@ -64,6 +64,7 @@ extern const AVCodecParser ff_mpegvideo_parser;
>  extern const AVCodecParser ff_opus_parser;
>  extern const AVCodecParser ff_png_parser;
>  extern const AVCodecParser ff_pnm_parser;
> +extern const AVCodecParser ff_prores_parser;
>  extern const AVCodecParser ff_qoi_parser;
>  extern const AVCodecParser ff_rv30_parser;
>  extern const AVCodecParser ff_rv40_parser;
> diff --git a/libavcodec/prores_parser.c b/libavcodec/prores_parser.c
> new file mode 100644
> index 0000000000..1299c7b642
> --- /dev/null
> +++ b/libavcodec/prores_parser.c
> @@ -0,0 +1,107 @@
> +/*
> + * ProRes bitstream parser
> + * Copyright (c) 2023 clarkh <hungkuishing@outlook.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 "parser.h"
> +#include "libavutil/intreadwrite.h"
> +#include "libavcodec/proresdata.h"
> +
> +typedef struct {
> +    ParseContext pc;
> +    int remaining;
> +    int overwrite;
> +} ProResParserContext;
> +
> +static int prores_find_frame_end(ProResParserContext *pctx, const uint8_t
> *buf, int buf_size)
> +{
> +    ParseContext *pc = &pctx->pc;
> +    uint64_t state64 = pc->state64;
> +    int pic_found = pc->frame_start_found;
> +    int i = 0;
> +
> +    if (!pic_found) {
> +        for (i = 0; i < buf_size; i++) {
> +            state64 = (state64 << 8) | buf[i];
> +            if ((state64 & 0xFFFFFFFF) == FRAME_ID) {
> +                i++;
> +                pic_found = 1;
> +                pctx->remaining = state64 >> 32;
> +                pctx->remaining -= pctx->overwrite;
> +                break;
> +            }
> +        }
> +    }
> +
> +    if (pic_found) {
> +        if (!buf_size)
> +            return END_NOT_FOUND;
> +
> +        if (pctx->remaining > buf_size) {
> +            pctx->remaining -= buf_size;
> +        } else {
> +            int remaining = pctx->remaining;
> +
> +            pc->frame_start_found = 0;
> +            pc->state64 = -1;
> +            pctx->remaining = 0;
> +            pctx->overwrite = 0;
> +            return remaining;
> +        }
> +    } else {
> +        pctx->overwrite += buf_size;
> +    }
> +
> +    pc->frame_start_found = pic_found;
> +    pc->state64 = state64;
> +
> +    return END_NOT_FOUND;
> +}
> +
> +static int prores_parse(AVCodecParserContext *s, AVCodecContext *avctx,
> +                      const uint8_t **poutbuf, int *poutbuf_size,
> +                      const uint8_t *buf, int buf_size)
> +{
> +    ProResParserContext *pctx = s->priv_data;
> +    ParseContext *pc = &pctx->pc;
> +    int next;
> +
> +    if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
> +        next = buf_size;
> +    } else {
> +        next = prores_find_frame_end(pctx, buf, buf_size);
> +        if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
> +            *poutbuf = NULL;
> +            *poutbuf_size = 0;
> +            return buf_size;
> +        }
> +    }
> +
> +    *poutbuf = buf;
> +    *poutbuf_size = buf_size;
> +
> +    return next;
> +}
> +
> +const AVCodecParser ff_prores_parser = {
> +    .codec_ids      = { AV_CODEC_ID_PRORES },
> +    .priv_data_size = sizeof(ProResParserContext),
> +    .parser_parse   = prores_parse,
> +    .parser_close   = ff_parse_close
> +};
> --
> 2.34.1
>
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