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

James Almer jamrial at gmail.com
Tue Jan 22 16:03:11 EET 2019


On 1/22/2019 10:30 AM, Paul B Mahol wrote:
> 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.

Don't get pissy about nothing. I asked nothing that deserves that kind
of reaction.

Doing mask & 0x8000 then shifting it left by one at every loop is weird
and one of the reasons why get_bits was written for. But do however you
prefer.

> 
>>
>>> +            }
>>> +        }
>>> +    }
>>> +}
>>> +
>>> +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.

INIT_CLEANUP is a flag to tell avcodec_open2() to call AVCodec.close()
if AVCodec.init() fails. Since s->prev_frame is the only thing allocated
by init(), calling close() after that failed to allocate is pointless.
s->prev_frame will be NULL and close() will be essentially a nop.

> 
>>
>> 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.

Right, missed it.

> 
>>
>>> +};
>>> 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 }
>>>  };
>>>
>>>
>>
>> _______________________________________________
>> ffmpeg-devel mailing list
>> ffmpeg-devel at ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>>
> _______________________________________________
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> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> 



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