ffmpeg学习十四：转码

2024-06-19 15:18
文章标签 学习 ffmpeg 十四 转码

本文主要是介绍ffmpeg学习十四：转码，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

转码指的是把一种音视频文件的格式（封装格式+编码格式）转换为另一种音视频文件的格式。其过程如图所示：
这里写图片描述
从图中可以得知，转码涉及了解封装，解编码，编码，再封装的过程。这个过程基本涵盖了之前文章的所有内容。对于一个视频文件而言，要把它转为另一种格式，意味着首先要改变它的封装格式，其次，视频文件可能包含多个流，比如视频流，音频流，字幕流等都需要重新编码。回顾之前的文章，我们单独分析了解封装，封装，编码音频，编码视频，解码视频的过程，唯独没有做解码音频的单独分析，但只要对解码视频比较了解，解码音频也很容易理解。因此，这篇文章分析的转码是之前所有文章的学习的知识的一次综合运用。
ffmpeg已经为我们提供了转码的例程，它是很好的学习教材。其路径为：doc/examples/transcoding.c

我下载的ffmpeg的版本是2.7版本，这个版本的这个例程能顺利编译，但是执行这个程序的时候，会报如下错误：
[libx264 @ 00021bb0]broken ffmpeg default settings detected
[libx264 @ 00021bb0]use an encoding preset (vpre)
解决方法：
参考ffmpeg x264编译与使用介绍这篇博客，

在avcodec_open函数之间增加如下几个AVCodecContext 的初始化：
/default settings for x264/
ctx->me_range = 16;
ctx->max_qdiff = 4;
ctx->qmin = 10;
ctx->qmax = 51;
ctx->qcompress = 0.6;

也就是在open_input_file和open_output_file函数的avcodec_open2函数之前，为AVCodecContext的实例做如上的附加配置，这样本人亲测可以解决这个问题。修改过的完整的代码如下：

#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavfilter/avfiltergraph.h>
#include <libavfilter/buffersink.h>
#include <libavfilter/buffersrc.h>
#include <libavutil/opt.h>
#include <libavutil/pixdesc.h>static AVFormatContext *ifmt_ctx;
static AVFormatContext *ofmt_ctx;
typedef struct FilteringContext {AVFilterContext *buffersink_ctx;AVFilterContext *buffersrc_ctx;AVFilterGraph *filter_graph;
} FilteringContext;
static FilteringContext *filter_ctx;static int open_input_file(const char *filename)
{int ret;unsigned int i;ifmt_ctx = NULL;if ((ret = avformat_open_input(&ifmt_ctx, filename, NULL, NULL)) < 0) {av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");return ret;}if ((ret = avformat_find_stream_info(ifmt_ctx, NULL)) < 0) {av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");return ret;}for (i = 0; i < ifmt_ctx->nb_streams; i++) {AVStream *stream;AVCodecContext *codec_ctx;stream = ifmt_ctx->streams[i];codec_ctx = stream->codec;/* Reencode video & audio and remux subtitles etc. */if (codec_ctx->codec_type == AVMEDIA_TYPE_VIDEO|| codec_ctx->codec_type == AVMEDIA_TYPE_AUDIO) {/* Open decoder */ret = avcodec_open2(codec_ctx,avcodec_find_decoder(codec_ctx->codec_id), NULL);if (ret < 0) {av_log(NULL, AV_LOG_ERROR, "Failed to open decoder for stream #%u\n", i);return ret;}}}av_dump_format(ifmt_ctx, 0, filename, 0);return 0;
}static int open_output_file(const char *filename)
{AVStream *out_stream;AVStream *in_stream;AVCodecContext *dec_ctx, *enc_ctx;AVCodec *encoder;int ret;unsigned int i;ofmt_ctx = NULL;avformat_alloc_output_context2(&ofmt_ctx, NULL, NULL, filename);if (!ofmt_ctx) {av_log(NULL, AV_LOG_ERROR, "Could not create output context\n");return AVERROR_UNKNOWN;}for (i = 0; i < ifmt_ctx->nb_streams; i++) {out_stream = avformat_new_stream(ofmt_ctx, NULL);if (!out_stream) {av_log(NULL, AV_LOG_ERROR, "Failed allocating output stream\n");return AVERROR_UNKNOWN;}in_stream = ifmt_ctx->streams[i];dec_ctx = in_stream->codec;enc_ctx = out_stream->codec;if (dec_ctx->codec_type == AVMEDIA_TYPE_VIDEO|| dec_ctx->codec_type == AVMEDIA_TYPE_AUDIO) {/* in this example, we choose transcoding to same codec */encoder = avcodec_find_encoder(dec_ctx->codec_id);if (!encoder) {av_log(NULL, AV_LOG_FATAL, "Necessary encoder not found\n");return AVERROR_INVALIDDATA;}/* In this example, we transcode to same properties (picture size,* sample rate etc.). These properties can be changed for output* streams easily using filters */if (dec_ctx->codec_type == AVMEDIA_TYPE_VIDEO) {enc_ctx->height = dec_ctx->height;enc_ctx->width = dec_ctx->width;enc_ctx->sample_aspect_ratio = dec_ctx->sample_aspect_ratio;/* take first format from list of supported formats */if (encoder->pix_fmts)enc_ctx->pix_fmt = encoder->pix_fmts[0];elseenc_ctx->pix_fmt = dec_ctx->pix_fmt;/* video time_base can be set to whatever is handy and supported by encoder */enc_ctx->time_base = dec_ctx->time_base;} else {enc_ctx->sample_rate = dec_ctx->sample_rate;enc_ctx->channel_layout = dec_ctx->channel_layout;enc_ctx->channels = av_get_channel_layout_nb_channels(enc_ctx->channel_layout);/* take first format from list of supported formats */enc_ctx->sample_fmt = encoder->sample_fmts[0];enc_ctx->time_base = (AVRational){1, enc_ctx->sample_rate};}/* Third parameter can be used to pass settings to encoder */ret = avcodec_open2(enc_ctx, encoder, NULL);if (ret < 0) {av_log(NULL, AV_LOG_ERROR, "Cannot open video encoder for stream #%u\n", i);return ret;}} else if (dec_ctx->codec_type == AVMEDIA_TYPE_UNKNOWN) {av_log(NULL, AV_LOG_FATAL, "Elementary stream #%d is of unknown type, cannot proceed\n", i);return AVERROR_INVALIDDATA;} else {/* if this stream must be remuxed */ret = avcodec_copy_context(ofmt_ctx->streams[i]->codec,ifmt_ctx->streams[i]->codec);if (ret < 0) {av_log(NULL, AV_LOG_ERROR, "Copying stream context failed\n");return ret;}}if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)enc_ctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;}av_dump_format(ofmt_ctx, 0, filename, 1);if (!(ofmt_ctx->oformat->flags & AVFMT_NOFILE)) {ret = avio_open(&ofmt_ctx->pb, filename, AVIO_FLAG_WRITE);if (ret < 0) {av_log(NULL, AV_LOG_ERROR, "Could not open output file '%s'", filename);return ret;}}/* init muxer, write output file header */ret = avformat_write_header(ofmt_ctx, NULL);if (ret < 0) {av_log(NULL, AV_LOG_ERROR, "Error occurred when opening output file\n");return ret;}return 0;
}static int init_filter(FilteringContext* fctx, AVCodecContext *dec_ctx,AVCodecContext *enc_ctx, const char *filter_spec)
{char args[512];int ret = 0;AVFilter *buffersrc = NULL;AVFilter *buffersink = NULL;AVFilterContext *buffersrc_ctx = NULL;AVFilterContext *buffersink_ctx = NULL;AVFilterInOut *outputs = avfilter_inout_alloc();AVFilterInOut *inputs  = avfilter_inout_alloc();AVFilterGraph *filter_graph = avfilter_graph_alloc();if (!outputs || !inputs || !filter_graph) {ret = AVERROR(ENOMEM);goto end;}if (dec_ctx->codec_type == AVMEDIA_TYPE_VIDEO) {buffersrc = avfilter_get_by_name("buffer");buffersink = avfilter_get_by_name("buffersink");if (!buffersrc || !buffersink) {av_log(NULL, AV_LOG_ERROR, "filtering source or sink element not found\n");ret = AVERROR_UNKNOWN;goto end;}snprintf(args, sizeof(args),"video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",dec_ctx->width, dec_ctx->height, dec_ctx->pix_fmt,dec_ctx->time_base.num, dec_ctx->time_base.den,dec_ctx->sample_aspect_ratio.num,dec_ctx->sample_aspect_ratio.den);ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in",args, NULL, filter_graph);if (ret < 0) {av_log(NULL, AV_LOG_ERROR, "Cannot create buffer source\n");goto end;}ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out",NULL, NULL, filter_graph);if (ret < 0) {av_log(NULL, AV_LOG_ERROR, "Cannot create buffer sink\n");goto end;}ret = av_opt_set_bin(buffersink_ctx, "pix_fmts",(uint8_t*)&enc_ctx->pix_fmt, sizeof(enc_ctx->pix_fmt),AV_OPT_SEARCH_CHILDREN);if (ret < 0) {av_log(NULL, AV_LOG_ERROR, "Cannot set output pixel format\n");goto end;}} else if (dec_ctx->codec_type == AVMEDIA_TYPE_AUDIO) {buffersrc = avfilter_get_by_name("abuffer");buffersink = avfilter_get_by_name("abuffersink");if (!buffersrc || !buffersink) {av_log(NULL, AV_LOG_ERROR, "filtering source or sink element not found\n");ret = AVERROR_UNKNOWN;goto end;}if (!dec_ctx->channel_layout)dec_ctx->channel_layout =av_get_default_channel_layout(dec_ctx->channels);snprintf(args, sizeof(args),"time_base=%d/%d:sample_rate=%d:sample_fmt=%s:channel_layout=0x%"PRIx64,dec_ctx->time_base.num, dec_ctx->time_base.den, dec_ctx->sample_rate,av_get_sample_fmt_name(dec_ctx->sample_fmt),dec_ctx->channel_layout);ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in",args, NULL, filter_graph);if (ret < 0) {av_log(NULL, AV_LOG_ERROR, "Cannot create audio buffer source\n");goto end;}ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out",NULL, NULL, filter_graph);if (ret < 0) {av_log(NULL, AV_LOG_ERROR, "Cannot create audio buffer sink\n");goto end;}ret = av_opt_set_bin(buffersink_ctx, "sample_fmts",(uint8_t*)&enc_ctx->sample_fmt, sizeof(enc_ctx->sample_fmt),AV_OPT_SEARCH_CHILDREN);if (ret < 0) {av_log(NULL, AV_LOG_ERROR, "Cannot set output sample format\n");goto end;}ret = av_opt_set_bin(buffersink_ctx, "channel_layouts",(uint8_t*)&enc_ctx->channel_layout,sizeof(enc_ctx->channel_layout), AV_OPT_SEARCH_CHILDREN);if (ret < 0) {av_log(NULL, AV_LOG_ERROR, "Cannot set output channel layout\n");goto end;}ret = av_opt_set_bin(buffersink_ctx, "sample_rates",(uint8_t*)&enc_ctx->sample_rate, sizeof(enc_ctx->sample_rate),AV_OPT_SEARCH_CHILDREN);if (ret < 0) {av_log(NULL, AV_LOG_ERROR, "Cannot set output sample rate\n");goto end;}} else {ret = AVERROR_UNKNOWN;goto end;}/* Endpoints for the filter graph. */outputs->name       = av_strdup("in");outputs->filter_ctx = buffersrc_ctx;outputs->pad_idx    = 0;outputs->next       = NULL;inputs->name       = av_strdup("out");inputs->filter_ctx = buffersink_ctx;inputs->pad_idx    = 0;inputs->next       = NULL;if (!outputs->name || !inputs->name) {ret = AVERROR(ENOMEM);goto end;}if ((ret = avfilter_graph_parse_ptr(filter_graph, filter_spec,&inputs, &outputs, NULL)) < 0)goto end;if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)goto end;/* Fill FilteringContext */fctx->buffersrc_ctx = buffersrc_ctx;fctx->buffersink_ctx = buffersink_ctx;fctx->filter_graph = filter_graph;end:avfilter_inout_free(&inputs);avfilter_inout_free(&outputs);return ret;
}static int init_filters(void)
{const char *filter_spec;unsigned int i;int ret;filter_ctx = av_malloc_array(ifmt_ctx->nb_streams, sizeof(*filter_ctx));if (!filter_ctx)return AVERROR(ENOMEM);for (i = 0; i < ifmt_ctx->nb_streams; i++) {filter_ctx[i].buffersrc_ctx  = NULL;filter_ctx[i].buffersink_ctx = NULL;filter_ctx[i].filter_graph   = NULL;if (!(ifmt_ctx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO|| ifmt_ctx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO))continue;if (ifmt_ctx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)filter_spec = "null"; /* passthrough (dummy) filter for video */elsefilter_spec = "anull"; /* passthrough (dummy) filter for audio */ret = init_filter(&filter_ctx[i], ifmt_ctx->streams[i]->codec,ofmt_ctx->streams[i]->codec, filter_spec);if (ret)return ret;}return 0;
}static int encode_write_frame(AVFrame *filt_frame, unsigned int stream_index, int *got_frame) {int ret;int got_frame_local;AVPacket enc_pkt;int (*enc_func)(AVCodecContext *, AVPacket *, const AVFrame *, int *) =(ifmt_ctx->streams[stream_index]->codec->codec_type ==AVMEDIA_TYPE_VIDEO) ? avcodec_encode_video2 : avcodec_encode_audio2;if (!got_frame)got_frame = &got_frame_local;av_log(NULL, AV_LOG_INFO, "Encoding frame\n");/* encode filtered frame */enc_pkt.data = NULL;enc_pkt.size = 0;av_init_packet(&enc_pkt);ret = enc_func(ofmt_ctx->streams[stream_index]->codec, &enc_pkt,filt_frame, got_frame);av_frame_free(&filt_frame);if (ret < 0)return ret;if (!(*got_frame))return 0;/* prepare packet for muxing */enc_pkt.stream_index = stream_index;av_packet_rescale_ts(&enc_pkt,ofmt_ctx->streams[stream_index]->codec->time_base,ofmt_ctx->streams[stream_index]->time_base);av_log(NULL, AV_LOG_DEBUG, "Muxing frame\n");/* mux encoded frame */ret = av_interleaved_write_frame(ofmt_ctx, &enc_pkt);return ret;
}static int filter_encode_write_frame(AVFrame *frame, unsigned int stream_index)
{int ret;AVFrame *filt_frame;av_log(NULL, AV_LOG_INFO, "Pushing decoded frame to filters\n");/* push the decoded frame into the filtergraph */ret = av_buffersrc_add_frame_flags(filter_ctx[stream_index].buffersrc_ctx,frame, 0);if (ret < 0) {av_log(NULL, AV_LOG_ERROR, "Error while feeding the filtergraph\n");return ret;}/* pull filtered frames from the filtergraph */while (1) {filt_frame = av_frame_alloc();if (!filt_frame) {ret = AVERROR(ENOMEM);break;}av_log(NULL, AV_LOG_INFO, "Pulling filtered frame from filters\n");ret = av_buffersink_get_frame(filter_ctx[stream_index].buffersink_ctx,filt_frame);if (ret < 0) {/* if no more frames for output - returns AVERROR(EAGAIN)* if flushed and no more frames for output - returns AVERROR_EOF* rewrite retcode to 0 to show it as normal procedure completion*/if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)ret = 0;av_frame_free(&filt_frame);break;}filt_frame->pict_type = AV_PICTURE_TYPE_NONE;ret = encode_write_frame(filt_frame, stream_index, NULL);if (ret < 0)break;}return ret;
}static int flush_encoder(unsigned int stream_index)
{int ret;int got_frame;if (!(ofmt_ctx->streams[stream_index]->codec->codec->capabilities &AV_CODEC_CAP_DELAY))return 0;while (1) {av_log(NULL, AV_LOG_INFO, "Flushing stream #%u encoder\n", stream_index);ret = encode_write_frame(NULL, stream_index, &got_frame);if (ret < 0)break;if (!got_frame)return 0;}return ret;
}int main(int argc, char **argv)
{int ret;AVPacket packet = { .data = NULL, .size = 0 };AVFrame *frame = NULL;enum AVMediaType type;unsigned int stream_index;unsigned int i;int got_frame;int (*dec_func)(AVCodecContext *, AVFrame *, int *, const AVPacket *);if (argc != 3) {av_log(NULL, AV_LOG_ERROR, "Usage: %s <input file> <output file>\n", argv[0]);return 1;}av_register_all();avfilter_register_all();if ((ret = open_input_file(argv[1])) < 0)goto end;if ((ret = open_output_file(argv[2])) < 0)goto end;if ((ret = init_filters()) < 0)goto end;/* read all packets */while (1) {if ((ret = av_read_frame(ifmt_ctx, &packet)) < 0)break;stream_index = packet.stream_index;type = ifmt_ctx->streams[packet.stream_index]->codec->codec_type;av_log(NULL, AV_LOG_DEBUG, "Demuxer gave frame of stream_index %u\n",stream_index);if (filter_ctx[stream_index].filter_graph) {av_log(NULL, AV_LOG_DEBUG, "Going to reencode&filter the frame\n");frame = av_frame_alloc();if (!frame) {ret = AVERROR(ENOMEM);break;}av_packet_rescale_ts(&packet,ifmt_ctx->streams[stream_index]->time_base,ifmt_ctx->streams[stream_index]->codec->time_base);dec_func = (type == AVMEDIA_TYPE_VIDEO) ? avcodec_decode_video2 :avcodec_decode_audio4;ret = dec_func(ifmt_ctx->streams[stream_index]->codec, frame,&got_frame, &packet);if (ret < 0) {av_frame_free(&frame);av_log(NULL, AV_LOG_ERROR, "Decoding failed\n");break;}if (got_frame) {frame->pts = av_frame_get_best_effort_timestamp(frame);ret = filter_encode_write_frame(frame, stream_index);av_frame_free(&frame);if (ret < 0)goto end;} else {av_frame_free(&frame);}} else {/* remux this frame without reencoding */av_packet_rescale_ts(&packet,ifmt_ctx->streams[stream_index]->time_base,ofmt_ctx->streams[stream_index]->time_base);ret = av_interleaved_write_frame(ofmt_ctx, &packet);if (ret < 0)goto end;}av_packet_unref(&packet);}/* flush filters and encoders */for (i = 0; i < ifmt_ctx->nb_streams; i++) {/* flush filter */if (!filter_ctx[i].filter_graph)continue;ret = filter_encode_write_frame(NULL, i);if (ret < 0) {av_log(NULL, AV_LOG_ERROR, "Flushing filter failed\n");goto end;}/* flush encoder */ret = flush_encoder(i);if (ret < 0) {av_log(NULL, AV_LOG_ERROR, "Flushing encoder failed\n");goto end;}}av_write_trailer(ofmt_ctx);
end:av_packet_unref(&packet);av_frame_free(&frame);for (i = 0; i < ifmt_ctx->nb_streams; i++) {avcodec_close(ifmt_ctx->streams[i]->codec);if (ofmt_ctx && ofmt_ctx->nb_streams > i && ofmt_ctx->streams[i] && ofmt_ctx->streams[i]->codec)avcodec_close(ofmt_ctx->streams[i]->codec);if (filter_ctx && filter_ctx[i].filter_graph)avfilter_graph_free(&filter_ctx[i].filter_graph);}av_free(filter_ctx);avformat_close_input(&ifmt_ctx);if (ofmt_ctx && !(ofmt_ctx->oformat->flags & AVFMT_NOFILE))avio_closep(&ofmt_ctx->pb);avformat_free_context(ofmt_ctx);if (ret < 0)av_log(NULL, AV_LOG_ERROR, "Error occurred: %s\n", av_err2str(ret));return ret ? 1 : 0;
}

转码的整个过程可用如下流程图来概述：
这里写图片描述

重要函数的简要介绍：
open_input_file()：打开输入文件，并初始化相关的结构体。
其中的avformat_open_input()函数可参考 ffmpeg学习五：avformat_open_input函数源码分析（以mp4文件为例）一文。avformat_find_stream_info()可参考ffmpeg学习七：avformat_find_stream_info函数源码分析一文。avcodec_open2()函数可参考 ffmpeg学习六：avcodec_open2函数源码分析一文。
open_output_file()：打开输出文件，并初始化相关的结构体。会写入格式相关的文件头部信息
init_filters()：初始化AVFilter相关的结构体。可参考ffmpeg学习十二：滤镜（实现视频缩放，裁剪，水印等）一文。
av_read_frame()：从输入文件中读取一个AVPacket。
avcodec_decode_video2()：解码一个视频AVPacket（存储H.264等压缩码流数据）为AVFrame（存储YUV等非压缩的像素数据）。
avcodec_decode_video4()：解码一个音频AVPacket（存储MP3等压缩码流数据）为AVFrame（存储PCM采样数据）。
filter_encode_write_frame()：首先会对AVFrame做滤镜处理，然后编码一个AVFrame，最后写入文件。
此外，音频编码可参考ffmpeg学习十：将pcm格式的音频编码为aac格式一文。
视频编码可参考ffmpeg学习八：软件生成yuv420p视频并将其编码为H264格式一文。
封装可参考 ffmpeg学习十一：封装音视频到同一个文件（muxing.c源码分析）一文。
解封装与解码可参考ffmpeg学习四：写第一个程序-视频解封装与解码一文。

这篇关于ffmpeg学习十四：转码的文章就介绍到这儿，希望我们推荐的文章对编程师们有所帮助！


http://www.chinasem.cn/article/1075395。

相关文章

Python中对FFmpeg封装开发库FFmpy详解

Python中对FFmpeg封装开发库FFmpy详解

《Python中对FFmpeg封装开发库FFmpy详解》：本文主要介绍Python中对FFmpeg封装开发库FFmpy,具有很好的参考价值,希望对大家有所帮助,如有错误或未考虑完全的地方,望不吝赐... 目录一、FFmpy简介与安装1.1 FFmpy概述1.2 安装方法二、FFmpy核心类与方法2.1 FF
阅读更多...
基于Linux的ffmpeg python的关键帧抽取

基于Linux的ffmpeg python的关键帧抽取

《基于Linux的ffmpegpython的关键帧抽取》本文主要介绍了基于Linux的ffmpegpython的关键帧抽取,实现以按帧或时间间隔抽取关键帧,文中通过示例代码介绍的非常详细,对大家的学... 目录1.FFmpeg的环境配置1) 创建一个虚拟环境envjavascript2) ffmpeg-py
阅读更多...
Go学习记录之runtime包深入解析

Go学习记录之runtime包深入解析

《Go学习记录之runtime包深入解析》Go语言runtime包管理运行时环境,涵盖goroutine调度、内存分配、垃圾回收、类型信息等核心功能,：本文主要介绍Go学习记录之runtime包的... 目录前言：一、runtime包内容学习1、作用：① Goroutine和并发控制：② 垃圾回收：③ 栈和
阅读更多...
Android学习总结之Java和kotlin区别超详细分析

Android学习总结之Java和kotlin区别超详细分析

《Android学习总结之Java和kotlin区别超详细分析》Java和Kotlin都是用于Android开发的编程语言,它们各自具有独特的特点和优势,：本文主要介绍Android学习总结之Ja... 目录一、空安全机制真题 1：Kotlin 如何解决 Java 的 NullPointerExceptio
阅读更多...
Python使用FFmpeg实现高效音频格式转换工具

Python使用FFmpeg实现高效音频格式转换工具

《Python使用FFmpeg实现高效音频格式转换工具》在数字音频处理领域,音频格式转换是一项基础但至关重要的功能,本文主要为大家介绍了Python如何使用FFmpeg实现强大功能的图形化音频转换工具... 目录概述功能详解软件效果展示主界面布局转换过程截图完成提示开发步骤详解1. 环境准备2. 项目功能结
阅读更多...
SpringBoot使用ffmpeg实现视频压缩

SpringBoot使用ffmpeg实现视频压缩

《SpringBoot使用ffmpeg实现视频压缩》FFmpeg是一个开源的跨平台多媒体处理工具集,用于录制,转换,编辑和流式传输音频和视频,本文将使用ffmpeg实现视频压缩功能,有需要的可以参考... 目录核心功能1.格式转换2.编解码3.音视频处理4.流媒体支持5.滤镜（Filter）安装配置linu
阅读更多...
重新对Java的类加载器的学习方式

重新对Java的类加载器的学习方式

《重新对Java的类加载器的学习方式》：本文主要介绍重新对Java的类加载器的学习方式,具有很好的参考价值,希望对大家有所帮助,如有错误或未考虑完全的地方,望不吝赐教... 目录1、介绍1.1、简介1.2、符号引用和直接引用1、符号引用2、直接引用3、符号转直接的过程2、加载流程3、类加载的分类3.1、显示
阅读更多...
Android NDK版本迭代与FFmpeg交叉编译完全指南

Android NDK版本迭代与FFmpeg交叉编译完全指南

《AndroidNDK版本迭代与FFmpeg交叉编译完全指南》在Android开发中,使用NDK进行原生代码开发是一项常见需求,特别是当我们需要集成FFmpeg这样的多媒体处理库时,本文将深入分析A... 目录一、android NDK版本迭代分界线二、FFmpeg交叉编译关键注意事项三、完整编译脚本示例四
阅读更多...
Java学习手册之Filter和Listener使用方法

Java学习手册之Filter和Listener使用方法

《Java学习手册之Filter和Listener使用方法》：本文主要介绍Java学习手册之Filter和Listener使用方法的相关资料,Filter是一种拦截器,可以在请求到达Servl... 目录一、Filter（过滤器）1. Filter 的工作原理2. Filter 的配置与使用二、Listen
阅读更多...
Python基于wxPython和FFmpeg开发一个视频标签工具

Python基于wxPython和FFmpeg开发一个视频标签工具

《Python基于wxPython和FFmpeg开发一个视频标签工具》在当今数字媒体时代,视频内容的管理和标记变得越来越重要,无论是研究人员需要对实验视频进行时间点标记,还是个人用户希望对家庭视频进行... 目录引言1. 应用概述2. 技术栈分析2.1 核心库和模块2.2 wxpython作为GUI选择的优
阅读更多...

Copyright China编程 23002807@qq.com

沪ICP备2023033072号-2