[FFmpeg-devel] [PATCH 2/2] MxPEG decoder
Stefano Sabatini
stefano.sabatini-lala
Tue Nov 2 01:23:54 CET 2010
On date Tuesday 2010-11-02 03:16:04 +0300, Anatoly Nenashev encoded:
> On 02.11.2010 01:32, Michael Niedermayer wrote:
[...]
> diff --git a/libavformat/Makefile b/libavformat/Makefile
> index 40adb53..ae6e05b 100644
> --- a/libavformat/Makefile
> +++ b/libavformat/Makefile
> @@ -147,6 +147,7 @@ OBJS-$(CONFIG_MTV_DEMUXER) += mtv.o
> OBJS-$(CONFIG_MVI_DEMUXER) += mvi.o
> OBJS-$(CONFIG_MXF_DEMUXER) += mxfdec.o mxf.o
> OBJS-$(CONFIG_MXF_MUXER) += mxfenc.o mxf.o audiointerleave.o
> +OBJS-$(CONFIG_MXG_DEMUXER) += mxg.o
> OBJS-$(CONFIG_NC_DEMUXER) += ncdec.o
> OBJS-$(CONFIG_NSV_DEMUXER) += nsvdec.o
> OBJS-$(CONFIG_NULL_MUXER) += nullenc.o
> diff --git a/libavformat/allformats.c b/libavformat/allformats.c
> index e35f4f8..4afbef5 100644
> --- a/libavformat/allformats.c
> +++ b/libavformat/allformats.c
> @@ -142,6 +142,7 @@ void av_register_all(void)
> REGISTER_DEMUXER (MVI, mvi);
> REGISTER_MUXDEMUX (MXF, mxf);
> REGISTER_MUXER (MXF_D10, mxf_d10);
> + REGISTER_DEMUXER (MXG, mxg);
> REGISTER_DEMUXER (NC, nc);
> REGISTER_DEMUXER (NSV, nsv);
> REGISTER_MUXER (NULL, null);
> diff --git a/libavformat/mxg.c b/libavformat/mxg.c
> new file mode 100644
> index 0000000..917cc47
> --- /dev/null
> +++ b/libavformat/mxg.c
> @@ -0,0 +1,195 @@
> +/*
> + * MxPEG Clip File demuxer
> + * Copyright (c) 2010 Anatoly Nenashev
> + *
> + * 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 "avformat.h"
> +#include "avio.h"
> +#include <libavutil/intreadwrite.h>
"libavutil/intreadwrite.h"
also should be listed before the local header (standard headers,
FFmpeg headers starting from libavutil... current dir headers)
> +
> +#define VIDEO_STREAM_INDEX 0
> +#define AUDIO_STREAM_INDEX 1
> +#define DEFAULT_PACKET_SIZE 1024
> +
> +
nit++: one empty line
> +typedef struct MXGContext {
> + uint8_t *buffer;
> + unsigned int buffer_size;
> + unsigned int current_pos;
> + uint16_t state;
> + int vop_found;
> + int64_t dts;
> +} MXGContext;
> +
> +static int mxg_read_header(AVFormatContext *s, AVFormatParameters *ap)
> +{
> + AVStream *video_st = 0, *audio_st = 0;
> + MXGContext *mxg = s->priv_data;
> +
> + /* video parameters will be extracted from the compressed bitstream */
> + video_st = av_new_stream(s, VIDEO_STREAM_INDEX);
> + if (!video_st)
> + return AVERROR(ENOMEM);
> + video_st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
> + video_st->codec->codec_id = CODEC_ID_MXPEG;
> + av_set_pts_info(video_st, 64, 1, 1000000);
> +
> + audio_st = av_new_stream(s, AUDIO_STREAM_INDEX);
> + if (!audio_st)
> + return AVERROR(ENOMEM);
> + audio_st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
> + audio_st->codec->codec_id = CODEC_ID_PCM_ALAW;
> + audio_st->codec->channels = 1;
> + audio_st->codec->sample_rate = 8000;
> + audio_st->codec->bits_per_coded_sample = 8;
> + audio_st->codec->block_align = 1;
> +
> + mxg->buffer = av_malloc(DEFAULT_PACKET_SIZE);
> + if (!mxg->buffer) {
> + av_log(s, AV_LOG_ERROR, "mxg demuxer error in av_malloc()\n");
> + return AVERROR(ENOMEM);
> + }
for all these memory error you can skip the error message, and simply
return ENOMEM
> + mxg->buffer_size = DEFAULT_PACKET_SIZE;
> + mxg->current_pos = 0;
> + mxg->state = 0;
> + mxg->vop_found = 0;
> + mxg->dts = AV_NOPTS_VALUE;
> +
> + return 0;
> +}
> +
> +static int mxg_read_packet(AVFormatContext *s, AVPacket *pkt)
> +{
> + int ret, size;
> + MXGContext *mxg = s->priv_data;
> +
> + while(!url_feof(s->pb) && !url_ferror(s->pb)) {
nit++: while_(
> + const uint8_t data = get_byte(s->pb);
> + unsigned int found_frame_end = 0;
> + mxg->state = (mxg->state << 8) | data;
> + mxg->buffer[mxg->current_pos++] = data;
> +
> + if (mxg->state == 0xffd9) {
> + found_frame_end = mxg->current_pos;
> + } else if (mxg->state == 0xffd8) {
> + if (mxg->vop_found) {
> + //emulating frame end
> + found_frame_end = mxg->current_pos - 2;
> + url_fseek(s->pb, -2, SEEK_CUR);
> + } else {
> + mxg->vop_found = 1;
> + }
> + } else if (mxg->state == 0xfffe) {
> + size = get_be16(s->pb);
> + if (url_feof(s->pb) || url_ferror(s->pb))
> + return AVERROR_EOF;
> +
> + if (mxg->current_pos > mxg->current_pos + size)
> + {
nit++: if (...)_{
> + av_log(s, AV_LOG_ERROR, "buffer overflow\n");
> + return AVERROR(ENOMEM);
> + }
> + mxg->buffer = av_fast_realloc(mxg->buffer, &mxg->buffer_size,
> + mxg->current_pos + size);
> + if (!mxg->buffer) {
> + av_log(s, AV_LOG_ERROR, "mxg demuxer error in av_fast_realloc()\n");
> + return AVERROR(ENOMEM);
> + }
ditto
> + if (size < 2) {
> + av_log(s, AV_LOG_ERROR, "wrong comment buffer size\n");
> + return AVERROR(EINVAL);
> + }
> + mxg->buffer[mxg->current_pos++] = size >> 8;
> + mxg->buffer[mxg->current_pos++] = size & 0xff;
> +
> + ret = get_buffer(s->pb, mxg->buffer + mxg->current_pos, size - 2);
> + if (ret < 0)
> + return ret;
> + if (ret >= 16 && !strncmp(mxg->buffer + mxg->current_pos, "MXF", 3)) {
> + mxg->dts = AV_RL64(mxg->buffer + mxg->current_pos + 8);
> + }
> + mxg->current_pos += ret;
> + mxg->state = 0;
> + } else if (mxg->state == 0xffed) {
> + mxg->current_pos -= 2;
> + size = get_be16(s->pb);
> + if (url_feof(s->pb) || url_ferror(s->pb))
> + return AVERROR_EOF;
> + if (size <= 14)
> + return AVERROR(EINVAL);
> + url_fskip(s->pb, 12);
> + if (url_feof(s->pb) || url_ferror(s->pb))
> + return AVERROR_EOF;
> + size -= 14;
> + ret = av_get_packet(s->pb, pkt, size);
> + if (ret < 0)
> + return ret;
> +
> + pkt->stream_index = AUDIO_STREAM_INDEX;
> + mxg->state = 0;
> +
> + return pkt->size;
> + }
> +
> + if (found_frame_end) {
> + mxg->vop_found = 0;
> + mxg->current_pos = 0;
> + ret = av_new_packet(pkt, found_frame_end);
> + if (ret < 0)
> + return ret;
> + memcpy(pkt->data, mxg->buffer, found_frame_end);
> + pkt->stream_index = VIDEO_STREAM_INDEX;
> + pkt->dts = mxg->dts;
> + return pkt->size;
> + }
> +
> + if (mxg->current_pos >= mxg->buffer_size) {
> + if (mxg->current_pos > mxg->current_pos + DEFAULT_PACKET_SIZE) {
> + av_log(s, AV_LOG_ERROR, "buffer overflow\n");
> + return AVERROR(ENOMEM);
> + }
> + mxg->buffer = av_fast_realloc(mxg->buffer, &mxg->buffer_size,
> + mxg->current_pos + DEFAULT_PACKET_SIZE);
> + if (!mxg->buffer) {
> + av_log(s, AV_LOG_ERROR, "mxg demuxer error in av_fast_realloc()\n");
> + return AVERROR(ENOMEM);
ditto
> + }
> + }
> + }
> +
> + return AVERROR_EOF;
> +}
> +
> +static int mxg_close(struct AVFormatContext *s)
> +{
> + MXGContext *mxg = s->priv_data;
> + av_freep(&mxg->buffer);
> + return 0;
> +}
> +
> +AVInputFormat mxg_demuxer = {
> + "mxg",
> + NULL_IF_CONFIG_SMALL("MxPEG Clip File Format"),
> + sizeof(MXGContext),
> + NULL,
> + mxg_read_header,
> + mxg_read_packet,
> + mxg_close,
> + .extensions = "mxg"
please use named fields, helps legibility and ease ABI break updates.
--
FFmpeg = Fantastic Furious Mournful Prodigious Elected God
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