[FFmpeg-devel] [PATCH] avcodec: add ARBC decoder

Paul B Mahol onemda at gmail.com
Tue Jan 22 15:30:33 EET 2019


On 1/22/19, James Almer <jamrial at gmail.com> wrote:
> On 1/22/2019 6:55 AM, Paul B Mahol wrote:
>> Thanks Kostya for great help in reversing binary.
>>
>> Signed-off-by: Paul B Mahol <onemda at gmail.com>
>> ---
>>  libavcodec/Makefile     |   1 +
>>  libavcodec/allcodecs.c  |   1 +
>>  libavcodec/arbc.c       | 203 ++++++++++++++++++++++++++++++++++++++++
>>  libavcodec/avcodec.h    |   1 +
>>  libavcodec/codec_desc.c |   7 ++
>>  libavformat/riff.c      |   1 +
>>  6 files changed, 214 insertions(+)
>>  create mode 100644 libavcodec/arbc.c
>>
>> diff --git a/libavcodec/Makefile b/libavcodec/Makefile
>> index bf746c143d..8e240aecf0 100644
>> --- a/libavcodec/Makefile
>> +++ b/libavcodec/Makefile
>> @@ -198,6 +198,7 @@ OBJS-$(CONFIG_APTX_HD_DECODER)         += aptx.o
>>  OBJS-$(CONFIG_APTX_HD_ENCODER)         += aptx.o
>>  OBJS-$(CONFIG_APNG_DECODER)            += png.o pngdec.o pngdsp.o
>>  OBJS-$(CONFIG_APNG_ENCODER)            += png.o pngenc.o
>> +OBJS-$(CONFIG_ARBC_DECODER)            += arbc.o
>>  OBJS-$(CONFIG_SSA_DECODER)             += assdec.o ass.o
>>  OBJS-$(CONFIG_SSA_ENCODER)             += assenc.o ass.o
>>  OBJS-$(CONFIG_ASS_DECODER)             += assdec.o ass.o
>> diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
>> index fe0376e27e..5cbb09a5a4 100644
>> --- a/libavcodec/allcodecs.c
>> +++ b/libavcodec/allcodecs.c
>> @@ -41,6 +41,7 @@ extern AVCodec ff_anm_decoder;
>>  extern AVCodec ff_ansi_decoder;
>>  extern AVCodec ff_apng_encoder;
>>  extern AVCodec ff_apng_decoder;
>> +extern AVCodec ff_arbc_decoder;
>>  extern AVCodec ff_asv1_encoder;
>>  extern AVCodec ff_asv1_decoder;
>>  extern AVCodec ff_asv2_encoder;
>> diff --git a/libavcodec/arbc.c b/libavcodec/arbc.c
>> new file mode 100644
>> index 0000000000..59a1d7bf0a
>> --- /dev/null
>> +++ b/libavcodec/arbc.c
>> @@ -0,0 +1,203 @@
>> +/*
>> + * Gryphon's Anim Compressor decoder
>> + * Copyright (c) 2018 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 <stdlib.h>
>> +#include <string.h>
>> +
>> +#include "libavutil/imgutils.h"
>> +#include "libavutil/internal.h"
>> +#include "libavutil/intreadwrite.h"
>> +#include "libavutil/mem.h"
>> +
>> +#include "avcodec.h"
>> +#include "bytestream.h"
>> +#include "internal.h"
>> +
>> +typedef struct ARBCContext {
>> +    GetByteContext gb;
>> +
>> +    AVFrame *prev_frame;
>> +} ARBCContext;
>> +
>> +static void fill_tile4(AVCodecContext *avctx, uint8_t *color, AVFrame
>> *frame)
>> +{
>> +    ARBCContext *s = avctx->priv_data;
>> +    GetByteContext *gb = &s->gb;
>> +    int nb_tiles = bytestream2_get_le16(gb);
>> +    int h = avctx->height - 1;
>> +
>> +    for (int i = 0; i < nb_tiles; i++) {
>> +        int y = bytestream2_get_byte(gb);
>> +        int x = bytestream2_get_byte(gb);
>> +        uint16_t mask = bytestream2_get_le16(gb);
>> +        int start_y = y * 4, start_x = x * 4;
>> +        int end_y = start_y + 4, end_x = start_x + 4;
>> +
>> +        for (int j = start_y; j < end_y; j++) {
>> +            for (int k = start_x; k < end_x; k++) {
>> +                if (mask & 0x8000) {
>> +                    if (j >= avctx->height || k >= avctx->width)
>> +                        continue;
>> +                    frame->data[0][frame->linesize[0] * (h - j) + 3 * k +
>> 0] = color[0];
>> +                    frame->data[0][frame->linesize[0] * (h - j) + 3 * k +
>> 1] = color[1];
>> +                    frame->data[0][frame->linesize[0] * (h - j) + 3 * k +
>> 2] = color[2];
>> +                }
>> +                mask = mask << 1;
>
> get_bits(). Same below.

Oh, come one, I had enough of this nonsense.
This is 16 bit number, using fucking get bits is overkill.
Get over it.

>
>> +            }
>> +        }
>> +    }
>> +}
>> +
>> +static void fill_tileX(AVCodecContext *avctx, int tile_width, int
>> tile_height,
>> +                       uint8_t *color, AVFrame *frame)
>> +{
>> +    ARBCContext *s = avctx->priv_data;
>> +    GetByteContext *gb = &s->gb;
>> +    const int step_h = tile_height / 4;
>> +    const int step_w = tile_width / 4;
>> +    int nb_tiles = bytestream2_get_le16(gb);
>> +    int h = avctx->height - 1;
>> +
>> +    for (int i = 0; i < nb_tiles; i++) {
>> +        int y = bytestream2_get_byte(gb);
>> +        int x = bytestream2_get_byte(gb);
>> +        uint16_t mask = bytestream2_get_le16(gb);
>> +        int start_y = y * tile_height, start_x = x * tile_width;
>> +        int end_y = start_y + tile_height, end_x = start_x + tile_width;
>> +
>> +        for (int j = start_y; j < end_y; j += step_h) {
>> +            for (int k = start_x; k < end_x; k += step_w) {
>> +                if (mask & 0x8000U) {
>> +                    for (int m = 0; m < step_h; m++) {
>> +                        for (int n = 0; n < step_w; n++) {
>> +                            if (j + m >= avctx->height || k + n >=
>> avctx->width)
>> +                                continue;
>> +                            frame->data[0][frame->linesize[0] * (h - (j +
>> m)) + 3 * (k + n) + 0] = color[0];
>> +                            frame->data[0][frame->linesize[0] * (h - (j +
>> m)) + 3 * (k + n) + 1] = color[1];
>> +                            frame->data[0][frame->linesize[0] * (h - (j +
>> m)) + 3 * (k + n) + 2] = color[2];
>> +                        }
>> +                    }
>> +                }
>> +                mask = mask << 1;
>> +            }
>> +        }
>> +    }
>> +}
>> +
>> +static int decode_frame(AVCodecContext *avctx, void *data,
>> +                        int *got_frame, AVPacket *avpkt)
>> +{
>> +    ARBCContext *s = avctx->priv_data;
>> +    AVFrame *const frame = data;
>
> No const.

Will remove.

>
>> +    int ret, nb_segments, keyframe = 1;
>> +
>> +    if (avpkt->size < 1)
>> +        return AVERROR_INVALIDDATA;
>> +
>> +    if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
>> +        return ret;
>> +
>> +    if (s->prev_frame->data[0]) {
>> +        ret = av_frame_copy(frame, s->prev_frame);
>> +        if (ret < 0)
>> +            return ret;
>> +    }
>> +
>> +    bytestream2_init(&s->gb, avpkt->data, avpkt->size);
>> +    bytestream2_skip(&s->gb, 8);
>> +    nb_segments = bytestream2_get_le16(&s->gb);
>> +    if (nb_segments == 0)
>> +        keyframe = 0;
>> +
>> +    for (int i = 0; i < nb_segments; i++) {
>> +        int resolution_flag;
>> +        uint8_t fill[3];
>> +
>> +        if (bytestream2_get_bytes_left(&s->gb) <= 0)
>> +            return AVERROR_INVALIDDATA;
>> +
>> +        fill[0] = bytestream2_get_byte(&s->gb);
>> +        bytestream2_skip(&s->gb, 1);
>> +        fill[1] = bytestream2_get_byte(&s->gb);
>> +        bytestream2_skip(&s->gb, 1);
>> +        fill[2] = bytestream2_get_byte(&s->gb);
>> +        bytestream2_skip(&s->gb, 1);
>> +        resolution_flag = bytestream2_get_byte(&s->gb);
>> +
>> +        if (resolution_flag & 0x10)
>> +            fill_tileX(avctx, 1024, 1024, fill, frame);
>> +        if (resolution_flag & 0x08)
>> +            fill_tileX(avctx, 256, 256, fill, frame);
>> +        if (resolution_flag & 0x04)
>> +            fill_tileX(avctx, 64, 64, fill, frame);
>> +        if (resolution_flag & 0x02)
>> +            fill_tileX(avctx, 16, 16, fill, frame);
>> +        if (resolution_flag & 0x01)
>> +            fill_tile4(avctx, fill, frame);
>> +    }
>> +
>> +    av_frame_unref(s->prev_frame);
>> +    if ((ret = av_frame_ref(s->prev_frame, frame)) < 0)
>> +        return ret;
>> +
>> +    frame->pict_type = keyframe ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;
>> +    frame->key_frame = keyframe;
>> +    *got_frame = 1;
>> +
>> +    return avpkt->size;
>> +}
>> +
>> +static av_cold int decode_init(AVCodecContext *avctx)
>> +{
>> +    ARBCContext *s = avctx->priv_data;
>> +
>> +    avctx->pix_fmt = AV_PIX_FMT_RGB24;
>> +
>> +    s->prev_frame = av_frame_alloc();
>> +    if (!s->prev_frame)
>> +        return AVERROR(ENOMEM);
>> +
>> +    return 0;
>> +}
>> +
>> +static av_cold int decode_close(AVCodecContext *avctx)
>> +{
>> +    ARBCContext *s = avctx->priv_data;
>> +
>> +    av_frame_free(&s->prev_frame);
>> +
>> +    return 0;
>> +}
>> +
>> +AVCodec ff_arbc_decoder = {
>> +    .name           = "arbc",
>> +    .long_name      = NULL_IF_CONFIG_SMALL("Gryphon's Anim Compressor"),
>> +    .type           = AVMEDIA_TYPE_VIDEO,
>> +    .id             = AV_CODEC_ID_ARBC,
>> +    .priv_data_size = sizeof(ARBCContext),
>> +    .init           = decode_init,
>> +    .decode         = decode_frame,
>> +    .close          = decode_close,
>> +    .capabilities   = AV_CODEC_CAP_DR1,
>> +    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE |
>> +                      FF_CODEC_CAP_INIT_CLEANUP,
>
> No need for this one. Only s->prev_frame is allocated in init(), and if
> that fails then close() would do nothing.

What? Nonsense.

>
> What's missing is AV_CODEC_CAP_DR1 seeing you use get_buffer.

Sorry, but you are not making any sense here. DR1 is right above.

>
>> +};
>> diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
>> index 90f9f08289..72dc277dfd 100644
>> --- a/libavcodec/avcodec.h
>> +++ b/libavcodec/avcodec.h
>> @@ -453,6 +453,7 @@ enum AVCodecID {
>>      AV_CODEC_ID_WCMV,
>>      AV_CODEC_ID_RASC,
>>      AV_CODEC_ID_HYMT,
>> +    AV_CODEC_ID_ARBC,
>>
>>      /* various PCM "codecs" */
>>      AV_CODEC_ID_FIRST_AUDIO = 0x10000,     ///< A dummy id pointing at
>> the start of audio codecs
>> diff --git a/libavcodec/codec_desc.c b/libavcodec/codec_desc.c
>> index 10a639101c..7b254c1d45 100644
>> --- a/libavcodec/codec_desc.c
>> +++ b/libavcodec/codec_desc.c
>> @@ -1698,6 +1698,13 @@ static const AVCodecDescriptor codec_descriptors[]
>> = {
>>          .long_name = NULL_IF_CONFIG_SMALL("HuffYUV MT"),
>>          .props     = AV_CODEC_PROP_INTRA_ONLY | AV_CODEC_PROP_LOSSLESS,
>>      },
>> +    {
>> +        .id        = AV_CODEC_ID_ARBC,
>> +        .type      = AVMEDIA_TYPE_VIDEO,
>> +        .name      = "arbc",
>> +        .long_name = NULL_IF_CONFIG_SMALL("Gryphon's Anim Compressor"),
>> +        .props     = AV_CODEC_PROP_LOSSY,
>> +    },
>>
>>      /* various PCM "codecs" */
>>      {
>> diff --git a/libavformat/riff.c b/libavformat/riff.c
>> index d5a509c8b9..8f0fd99e22 100644
>> --- a/libavformat/riff.c
>> +++ b/libavformat/riff.c
>> @@ -476,6 +476,7 @@ const AVCodecTag ff_codec_bmp_tags[] = {
>>      { AV_CODEC_ID_WCMV,         MKTAG('W', 'C', 'M', 'V') },
>>      { AV_CODEC_ID_RASC,         MKTAG('R', 'A', 'S', 'C') },
>>      { AV_CODEC_ID_HYMT,         MKTAG('H', 'Y', 'M', 'T') },
>> +    { AV_CODEC_ID_ARBC,         MKTAG('A', 'R', 'B', 'C') },
>>      { AV_CODEC_ID_NONE,         0 }
>>  };
>>
>>
>
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