On Sat, Jun 27, 2020 at 12:35:17PM +0530, gautamr...@gmail.com wrote:
> From: Gautam Ramakrishnan <gautamr...@gmail.com>
>
> This patch adds a pgx decoder.
> ---
> Changelog | 1 +
> doc/general.texi | 2 +
> libavcodec/Makefile | 1 +
> libavcodec/allcodecs.c | 1 +
> libavcodec/codec_desc.c | 7 ++
> libavcodec/codec_id.h | 1 +
> libavcodec/pgxdec.c | 184 ++++++++++++++++++++++++++++++++++++++++
> libavcodec/version.h | 2 +-
> 8 files changed, 198 insertions(+), 1 deletion(-)
> create mode 100644 libavcodec/pgxdec.c
>
> diff --git a/Changelog b/Changelog
> index a60e7d2eb8..1bb9931c0d 100644
> --- a/Changelog
> +++ b/Changelog
> @@ -4,6 +4,7 @@ releases are sorted from youngest to oldest.
> version <next>:
> - AudioToolbox output device
> - MacCaption demuxer
> +- PGX decoder
>
>
> version 4.3:
> diff --git a/doc/general.texi b/doc/general.texi
> index ea34b963b5..53d556c56c 100644
> --- a/doc/general.texi
> +++ b/doc/general.texi
> @@ -751,6 +751,8 @@ following image formats are supported:
> @tab Portable GrayMap image
> @item PGMYUV @tab X @tab X
> @tab PGM with U and V components in YUV 4:2:0
> +@item PGX @tab @tab X
> + @tab PGX file decoder
> @item PIC @tab @tab X
> @tab Pictor/PC Paint
> @item PNG @tab X @tab X
> diff --git a/libavcodec/Makefile b/libavcodec/Makefile
> index 5a6ea59715..12aa43fe51 100644
> --- a/libavcodec/Makefile
> +++ b/libavcodec/Makefile
> @@ -536,6 +536,7 @@ OBJS-$(CONFIG_PGM_ENCODER) += pnmenc.o
> OBJS-$(CONFIG_PGMYUV_DECODER) += pnmdec.o pnm.o
> OBJS-$(CONFIG_PGMYUV_ENCODER) += pnmenc.o
> OBJS-$(CONFIG_PGSSUB_DECODER) += pgssubdec.o
> +OBJS-$(CONFIG_PGX_DECODER) += pgxdec.o
> OBJS-$(CONFIG_PICTOR_DECODER) += pictordec.o cga_data.o
> OBJS-$(CONFIG_PIXLET_DECODER) += pixlet.o
> OBJS-$(CONFIG_PJS_DECODER) += textdec.o ass.o
> diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
> index fa0c08d42e..a5048290f7 100644
> --- a/libavcodec/allcodecs.c
> +++ b/libavcodec/allcodecs.c
> @@ -238,6 +238,7 @@ extern AVCodec ff_pgm_encoder;
> extern AVCodec ff_pgm_decoder;
> extern AVCodec ff_pgmyuv_encoder;
> extern AVCodec ff_pgmyuv_decoder;
> +extern AVCodec ff_pgx_decoder;
> extern AVCodec ff_pictor_decoder;
> extern AVCodec ff_pixlet_decoder;
> extern AVCodec ff_png_encoder;
> diff --git a/libavcodec/codec_desc.c b/libavcodec/codec_desc.c
> index 9f8847544f..67e0a3055c 100644
> --- a/libavcodec/codec_desc.c
> +++ b/libavcodec/codec_desc.c
> @@ -1405,6 +1405,13 @@ static const AVCodecDescriptor codec_descriptors[] = {
> .long_name = NULL_IF_CONFIG_SMALL("AVS2-P2/IEEE1857.4"),
> .props = AV_CODEC_PROP_LOSSY,
> },
> + {
> + .id = AV_CODEC_ID_PGX,
> + .type = AVMEDIA_TYPE_VIDEO,
> + .name = "pgx",
> + .long_name = NULL_IF_CONFIG_SMALL("PGX (JPEG2000 Test Format)"),
> + .props = AV_CODEC_PROP_INTRA_ONLY | AV_CODEC_PROP_LOSSLESS,
> + },
> {
> .id = AV_CODEC_ID_Y41P,
> .type = AVMEDIA_TYPE_VIDEO,
> diff --git a/libavcodec/codec_id.h b/libavcodec/codec_id.h
> index d885962c9c..896ecb0ce0 100644
> --- a/libavcodec/codec_id.h
> +++ b/libavcodec/codec_id.h
> @@ -241,6 +241,7 @@ enum AVCodecID {
> AV_CODEC_ID_SCREENPRESSO,
> AV_CODEC_ID_RSCC,
> AV_CODEC_ID_AVS2,
> + AV_CODEC_ID_PGX,
>
> AV_CODEC_ID_Y41P = 0x8000,
> AV_CODEC_ID_AVRP,
> diff --git a/libavcodec/pgxdec.c b/libavcodec/pgxdec.c
> new file mode 100644
> index 0000000000..df5f5028cd
> --- /dev/null
> +++ b/libavcodec/pgxdec.c
> @@ -0,0 +1,184 @@
> +/*
> + * PGX image format
> + * Copyright (c) 2020 Gautam Ramakrishnan
> + *
> + * 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 "avcodec.h"
> +#include "internal.h"
> +#include "bytestream.h"
> +
> +typedef struct PGXContext {
> + GetByteContext g;
> + int depth;
> + int sign;
> + int width;
> + int height;
> +} PGXContext;
> +
> +static int pgx_get_number(AVCodecContext *avctx, PGXContext * const s) {
> + int ret = -1;
> + char digit;
> +
> + while (1) {
> + if (!bytestream2_get_bytes_left(&s->g))
> + return AVERROR_INVALIDDATA;
> + digit = bytestream2_get_byte(&s->g);
> + if (digit == ' ' || digit == 0xA || digit == 0xD) {
> + break;
> + } else if (digit < '0' || digit > '9') {
> + return AVERROR_INVALIDDATA;
> + }
> + if (ret < 0)
> + ret = 0;
> + ret = 10 * ret + (digit - '0');
this could overflow
> + }
> +
> + if (ret >= 0)
> + return ret;
> + return AVERROR_INVALIDDATA;
> +}
> +
> +static int ff_pgx_decode_header(AVCodecContext *avctx, PGXContext * s)
> +{
> + const char *header_start = "PG ML ";
> + int byte;
> +
> + if (bytestream2_get_bytes_left(&s->g) < 13) {
> + return AVERROR_INVALIDDATA;
> + }
> + // Checks whether file starts with "PG ML "
> + if (memcmp(header_start, s->g.buffer, 6))
> + return AVERROR_INVALIDDATA;
> + bytestream2_skip(&s->g, 6);
> +
> + // Is the component signed?
> + byte = bytestream2_peek_byte(&s->g);
> + if (byte == '+') {
> + s->sign = 0;
> + bytestream2_skip(&s->g, 1);
> + } else if (byte == '-') {
> + s->sign = 1;
> + bytestream2_skip(&s->g, 1);
> + }
> +
> + if (bytestream2_peek_byte(&s->g) == ' ')
> + bytestream2_skip(&s->g, 1);
> + s->depth = pgx_get_number(avctx, s);
> + s->width = pgx_get_number(avctx, s);
> + s->height = pgx_get_number(avctx, s);
> + if (bytestream2_peek_byte(&s->g) == 0xA)
> + bytestream2_skip(&s->g, 1);
pgx_get_number can return errors
the code using it does not check for them
> + return 0;
> +}
> +
> +static inline int write_frame_8(AVPacket *avpkt, AVFrame *frame, PGXContext
> * const s)
> +{
> + int i, j;
> + for (i = 0; i < s->height; i++) {
> + uint8_t *line = frame->data[0] + i * frame->linesize[0];
> + for (j = 0; j < s->width; j++) {
> + int val;
> + if (bytestream2_get_bytes_left(&s->g) < 1)
> + return AVERROR_INVALIDDATA;
> + if (s->sign) {
> + val = bytestream2_get_byte(&s->g) + (1 << (s->depth - 1));
> + val <<= (8 - s->depth);
> + *(line + j) = val;
> + } else {
> + val = bytestream2_get_byteu(&s->g);
> + val <<= (8 - s->depth);
> + *(line + j) = val;
> + }
> + }
> + line += frame->linesize[0];
> + }
> + return 0;
> +}
> +
> +static inline int write_frame_16(AVPacket *avpkt, AVFrame *frame, PGXContext
> * const s)
> +{
> + int i, j;
> + for (i = 0; i < s->height; i++) {
> + uint16_t *line = (uint16_t*)frame->data[0] + i*frame->linesize[0]/2;
> + for (j = 0; j < s->width; j++) {
> + int val;
> + if (bytestream2_get_bytes_left(&s->g) < 2)
> + return AVERROR_INVALIDDATA;
> + if (s->sign) {
> + val = (int16_t)bytestream2_get_be16(&s->g) + (1 << (s->depth
> - 1));
> + val <<= (16 - s->depth);
> + *(line + j) = val;
> + } else {
> + val = bytestream2_get_be16u(&s->g);
> + val <<= (16 - s->depth);
> + *(line + j) = val;
> + }
> + }
> + line += frame->linesize[0]/2;
> + }
> + return 0;
> +}
> +
> +static int pgx_decode_frame(AVCodecContext *avctx, void *data,
> + int *got_frame, AVPacket *avpkt)
> +{
> + PGXContext *s = avctx->priv_data;
> + AVFrame *p = data;
> + int ret;
> + int bpp;
> + bytestream2_init(&s->g, avpkt->data, avpkt->size);
> + if ((ret = ff_pgx_decode_header(avctx, s)) < 0)
> + return ret;
> +
> + if (ret = ff_set_dimensions(avctx, s->width, s->height) < 0)
> + return ret;
> +
> + if (s->depth <= 8) {
> + avctx->pix_fmt = AV_PIX_FMT_GRAY8;
> + bpp = 8;
depth = 0 is valid ?, it would end in here
thx
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Rewriting code that is poorly written but fully understood is good.
Rewriting code that one doesnt understand is a sign that one is less smart
then the original author, trying to rewrite it will not make it better.
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