.简介：把上一篇文章中的demuxer加入ffmpeg源码中去，使可以用命令行方式调用自定义的demuxer
第一步：
在libavformat目录下新建mkdemuxer.c和mkdemuxer.h，代码如下：
mkdemuxer.c：
- /*
- *实现一个自己的demuxer并加入到demuxer链中去
- *作者：缪国凯（MK）
- *821486004@qq.com
- *2015-6-3
- */
- #include "mkdemuxer.h"
- typedef struct MKVideoDemuxerContext {
- const AVClass *pclass; /**< Class for private options. */
- int width, height; /**< Integers describing video size, set by a private option. */
- char *pixel_format; /**< Set by a private option. */
- AVRational framerate; /**< AVRational describing framerate, set by a private option. */
- } MKVideoDemuxerContext;
- int mkvideo_read_header(AVFormatContext *ctx)
- {
- MKVideoDemuxerContext *s = ctx->priv_data;
- enum AVPixelFormat pix_fmt;
- AVStream *st;
- st = avformat_new_stream(ctx, NULL);
- if (!st)
- return AVERROR(ENOMEM);
- st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
- st->codec->codec_id = ctx->iformat->raw_codec_id;
- //这里就简单的直接赋值为420p
- pix_fmt = AV_PIX_FMT_YUV420P;
- st->time_base.num = s->framerate.den;
- st->time_base.den = s->framerate.num;
- st->pts_wrap_bits = 64;
- st->codec->width = s->width;
- st->codec->height = s->height;
- st->codec->pix_fmt = pix_fmt;
- AVRational tmpRa;
- tmpRa.den = 1;
- tmpRa.num = 8;
- st->codec->bit_rate = av_rescale_q(avpicture_get_size(st->codec->pix_fmt, s->width, s->height),
- tmpRa, st->time_base);
- return 0;
- }
- int mkvideo_read_packet(AVFormatContext *s, AVPacket *pkt)
- {
- int packet_size, ret, width, height;
- AVStream *st = s->streams[0];
- width = st->codec->width;
- height = st->codec->height;
- packet_size = avpicture_get_size(st->codec->pix_fmt, width, height);
- if (packet_size < 0)
- return -1;
- ret = av_get_packet(s->pb, pkt, packet_size);
- pkt->pts = pkt->dts = pkt->pos / packet_size;
- pkt->stream_index = 0;
- if (ret < 0)
- return ret;
- return 0;
- }
- #define OFFSET(x) offsetof(MKVideoDemuxerContext, x)
- #define DEC AV_OPT_FLAG_DECODING_PARAM
- static const AVOption mk_options[] =
- {
- { "video_size", "set frame size", OFFSET(width), AV_OPT_TYPE_IMAGE_SIZE, {.str = NULL}, 0, 0, DEC },
- { "pixel_format", "set pixel format", OFFSET(pixel_format), AV_OPT_TYPE_STRING, {.str = "yuv420p"}, 0, 0, DEC },
- { "framerate", "set frame rate", OFFSET(framerate), AV_OPT_TYPE_VIDEO_RATE, {.str = "25"}, 0, 0, DEC },
- { NULL },
- };
- static const AVClass mk_demuxer_class = {
- .class_name = "mk video demuxer",
- .item_name = av_default_item_name,
- .option = mk_options,
- .version = LIBAVUTIL_VERSION_INT,
- };
- AVInputFormat ff_mk_demuxer = {
- .name = "mk",
- .long_name = NULL_IF_CONFIG_SMALL("MK Video Container"),
- .flags = AVFMT_GENERIC_INDEX,
- .extensions = "mk",
- .priv_class = &mk_demuxer_class,
- .raw_codec_id = AV_CODEC_ID_RAWVIDEO,
- .priv_data_size = sizeof(MKVideoDemuxerContext),
- .read_header = mkvideo_read_header,
- .read_packet = mkvideo_read_packet,
- };
mkdemuxer.h：
- /*
- *实现一个自己的demuxer并加入到demuxer链中去
- *作者：缪国凯（MK）
- *821486004@qq.com
- *2015-6-3
- */
- #ifndef AVFORMAT_MKDEMUXER_H
- #define AVFORMAT_MKDEMUXER_H
- #include "libavutil/opt.h"
- #include "avformat.h"
- int mkvideo_read_header(AVFormatContext *ctx);
- int mkvideo_read_packet(AVFormatContext *s, AVPacket *pkt);
- #endif //AVFORMAT_MKDEMUXER_H
第二步：
在libavformat下的allformats.c的av_register_all里加入：
- REGISTER_DEMUXER (MK, mk);//add ByMK for mk demuxer
第三步：
在libavformat目录下的makefile文件的# muxers/demuxers后加入：
- OBJS-$(CONFIG_MK_DEMUXER) += mkdemuxer.o
第四步：
在ffmpeg根目录的config.h里加入：
- #define CONFIG_MK_DEMUXER 1
第五步：
如果不想重新configure，则在ffmpeg根目录的config.mak文件中加入：
- CONFIG_MK_DEMUXER=yes
OK，按照正常的编译去编译ffmpeg，然后运行ffmpeg.exe输入ffmpeg -formats 看到有mk这个muxer了，如下：
- DE mk mk (MK Video Container)
- E mkvtimestamp_v2 extract pts as timecode v2 format, as defined by mkvtoolnix
- DE mlp raw MLP
- D mlv Magic Lantern Video (MLV)
- D mm American Laser Games MM
- DE mmf Yamaha SMAF
- E mov QuickTime / MOV
再试一下命令：ffmpeg -s 1280x720 -i test.mk -y test.avi。
注意：当.mk格式作为输入的时候，必须加输入参数-s 分辨率，就和yuv作为输入一样（因为从本质上讲就是yuv...）。
成功！OK，大功告成。
原理在上一篇的博文中已经讲到了，下一步，实现自己的encoder。
from:http://blog.csdn.net/dancing_night/article/details/46348515
