Re: [FFmpeg-devel] [PATCH] avcodec: add RTV1 decoder

[James Almer <jamrial@gmail.com>]

> From cdd867aa1c88fa8b89dfe473ae0e2caf69c74313 Mon Sep 17 00:00:00 2001
> From: Paul B Mahol <onemda@gmail.com>
> Date: Sat, 3 Jun 2023 12:29:25 +0200
> Subject: [PATCH] avcodec: add RTV1 decoder
> 
> Signed-off-by: Paul B Mahol <onemda@gmail.com>
> ---
>  libavcodec/Makefile     |   1 +
>  libavcodec/allcodecs.c  |   1 +
>  libavcodec/codec_desc.c |   7 ++
>  libavcodec/codec_id.h   |   1 +
>  libavcodec/rtv1.c       | 141 ++++++++++++++++++++++++++++++++++++++++
>  libavformat/riff.c      |   1 +
>  6 files changed, 152 insertions(+)
>  create mode 100644 libavcodec/rtv1.c

Don't forget to bump minor version.

[...]

> diff --git a/libavcodec/rtv1.c b/libavcodec/rtv1.c
> new file mode 100644
> index 0000000000..953f915c83
> --- /dev/null
> +++ b/libavcodec/rtv1.c
> @@ -0,0 +1,141 @@
> +/*
> + * RTV1 decoder
> + * Copyright (c) 2023 Paul B Mahol
> + *
> + * 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 <stdio.h>
> +#include <string.h>
> +
> +#include "avcodec.h"
> +#include "bytestream.h"
> +#include "codec_internal.h"
> +#include "decode.h"
> +#include "texturedsp.h"
> +#include "thread.h"
> +
> +static int decode_rtv1(GetByteContext *gb, uint8_t *dst, int linesize,

ptrdiff_t linesize

> +                       int width, int height, int flag,
> +                       int (*dxt1_block)(uint8_t *dst, ptrdiff_t stride, const uint8_t *block))
> +{
> +    uint8_t block[8] = { 0 };
> +    int run = 0;
> +
> +    for (int y = 0; y < height; y += 4) {
> +        for (int x = 0; x < width * 4; x += 16) {
> +            int mode = 0;
> +
> +            if (run && --run > 0) {
> +                dxt1_block(dst + x, linesize, block);
> +            } else {
> +                int a, b;
> +
> +                if (bytestream2_get_bytes_left(gb) < 4)
> +                    break;
> +
> +                a = bytestream2_get_le16u(gb);
> +                b = bytestream2_get_le16u(gb);
> +                if (a == b && flag) {

4 bytes for a boolean value? Geez.

> +                    AV_WL32(block + 4, 0);
> +                } else if (a == 1 && b == 0xffff) {
> +                    mode = 1;
> +                } else if (b && a == 0) {
> +                    run = b;
> +                } else {
> +                    AV_WL16(block,     a);
> +                    AV_WL16(block + 2, b);
> +                    AV_WL32(block + 4, bytestream2_get_le32(gb));
> +                }
> +                if (run && !mode) {
> +                    dxt1_block(dst + x, linesize, block);
> +                } else if (!mode) {
> +                    AV_WL16(block,     a);
> +                    AV_WL16(block + 2, b);
> +                    dxt1_block(dst + x, linesize, block);
> +                } else {
> +                    if (bytestream2_get_bytes_left(gb) < 12 * 4)
> +                        break;
> +
> +                    for (int by = 0; by < 4; by++) {
> +                        for (int bx = 0; bx < 4; bx++)
> +                            AV_WL32(dst + x + bx * 4 + by * linesize, bytestream2_get_le24u(gb));
> +                    }
> +                }
> +            }
> +        }
> +
> +        dst += linesize * 4;
> +    }
> +
> +    return 0;
> +}
> +
> +static int decode_frame(AVCodecContext *avctx, AVFrame *p,
> +                        int *got_frame, AVPacket *avpkt)
> +{
> +    int ret, width, height, flags;
> +    TextureDSPContext dsp;
> +    GetByteContext gb;
> +    ptrdiff_t linesize;
> +    uint8_t *dst;
> +
> +    if (avpkt->size < 22)
> +        return AVERROR_INVALIDDATA;
> +
> +    ff_texturedsp_init(&dsp);

This should be in an init() function, not called for every frame.

> +
> +    bytestream2_init(&gb, avpkt->data, avpkt->size);
> +
> +    if (bytestream2_get_le32(&gb) != MKTAG('D','X','T','1'))

Is this really a RivaTuner codec and not just raw texture if the first 
four bytes are the name of the texture type?

> +        return AVERROR_INVALIDDATA;
> +    flags = bytestream2_get_le32(&gb);
> +
> +    width = bytestream2_get_le32(&gb);
> +    height = bytestream2_get_le32(&gb);
> +    ret = ff_set_dimensions(avctx, width, height);
> +    if (ret < 0)
> +        return ret;
> +
> +    avctx->coded_width  = FFALIGN(avctx->width,  4);
> +    avctx->coded_height = FFALIGN(avctx->height, 4);

This should also be in avcodec_align_dimensions2(), otherwise it will 
not be taken into account by ff_thread_get_buffer().

> +    avctx->pix_fmt = AV_PIX_FMT_BGR0;

Move this to the init function too while at it.

> +
> +    if ((ret = ff_thread_get_buffer(avctx, p, 0)) < 0)
> +        return ret;
> +
> +    dst = p->data[0] + p->linesize[0] * (avctx->coded_height - 1);
> +    linesize = -p->linesize[0];
> +
> +    decode_rtv1(&gb, dst, linesize, width, height, flags, dsp.dxt1_block);
> +
> +    p->pict_type = AV_PICTURE_TYPE_I;
> +    p->flags |= AV_FRAME_FLAG_KEY;
> +
> +    *got_frame = 1;
> +
> +    return avpkt->size;
> +}
> +
> +const FFCodec ff_rtv1_decoder = {
> +    .p.name           = "rtv1",
> +    CODEC_LONG_NAME("RTV1 (RivaTuner Video)"),
> +    .p.type           = AVMEDIA_TYPE_VIDEO,
> +    .p.id             = AV_CODEC_ID_RTV1,
> +    FF_CODEC_DECODE_CB(decode_frame),
> +    .p.capabilities   = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS,
> +};
> diff --git a/libavformat/riff.c b/libavformat/riff.c
> index 7319406b39..4279071159 100644
> --- a/libavformat/riff.c
> +++ b/libavformat/riff.c
> @@ -501,6 +501,7 @@ const AVCodecTag ff_codec_bmp_tags[] = {
>      { AV_CODEC_ID_NOTCHLC,      MKTAG('n', 'l', 'c', '1') },
>      { AV_CODEC_ID_VQC,          MKTAG('V', 'Q', 'C', '1') },
>      { AV_CODEC_ID_VQC,          MKTAG('V', 'Q', 'C', '2') },
> +    { AV_CODEC_ID_RTV1,         MKTAG('R', 'T', 'V', '1') },
>      { AV_CODEC_ID_NONE,         0 }
>  };
>  
> -- 
> 2.39.1
> 
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