dav转mp4 代码实现，

Dav通常是指DAV (WebDAV) 协议，它是HTTP协议的一个扩展，用于访问和管理远程文件系统。而MP4是一种常见的视频文件格式。如果你想要将支持DAV协议的网络共享资源转换成MP4格式，这通常是通过下载文件到本地然后再进行转换。下面是一个简单的Python示例，使用`pydub`库来处理音频，对于视频可能需要第三方库如`moviepy`：

from pydub import AudioSegment
import requests

# 假设URL是DAV服务器上的音频文件
url = "http://your_dav_url.mp3"
response = requests.get(url)
audio_data = response.content

# 使用pydub解析并保存为MP3
audio = AudioSegment.from_mp3(BytesIO(audio_data))
audio.export("output.mp3", format="mp3")

# 对于视频，你可以使用类似的方法先下载然后用FFmpeg等工具转换
# 例如，FFmpeg命令行：
# !ffmpeg -i input.webm -c:v libx264 -preset slow -crf 22 output.mp4

# 注意：上述代码仅适用于网络资源并且有对应的解码库支持，实际操作可能会受限于权限和服务器设置。

相关问题

ffmepg c语言 dav转mp4 vs代码

你可以使用FFmpeg库来将DAV视频文件转换为MP4格式。以下是一个简单的C语言程序，使用FFmpeg实现此功能：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavutil/imgutils.h>
#include <libavutil/opt.h>
#include <libswscale/swscale.h>

int main(int argc, char *argv[]) {
    AVFormatContext *input_ctx = NULL, *output_ctx = NULL;
    AVCodecContext *decoder_ctx = NULL, *encoder_ctx = NULL;
    AVCodec *decoder = NULL, *encoder = NULL;
    AVFrame *frame = NULL, *tmp_frame = NULL;
    AVPacket *pkt = NULL;
    int ret = 0, video_stream_index = -1, len = 0;
    char *input_file = NULL, *output_file = NULL;

    if (argc != 3) {
        fprintf(stderr, "Usage: %s <input_file> <output_file>\n", argv[0]);
        exit(1);
    }

    input_file = argv[1];
    output_file = argv[2];

    // open input file
    if ((ret = avformat_open_input(&input_ctx, input_file, NULL, NULL)) < 0) {
        fprintf(stderr, "Failed to open input file: %s\n", av_err2str(ret));
        goto end;
    }

    // retrieve stream information
    if ((ret = avformat_find_stream_info(input_ctx, NULL)) < 0) {
        fprintf(stderr, "Failed to retrieve input stream information: %s\n", av_err2str(ret));
        goto end;
    }

    // find video stream
    for (int i = 0; i < input_ctx->nb_streams; i++) {
        if (input_ctx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
            video_stream_index = i;
            break;
        }
    }

    if (video_stream_index == -1) {
        fprintf(stderr, "Failed to find video stream\n");
        goto end;
    }

    // allocate decoder context
    decoder = avcodec_find_decoder(input_ctx->streams[video_stream_index]->codecpar->codec_id);
    if (!decoder) {
        fprintf(stderr, "Failed to find decoder\n");
        goto end;
    }

    decoder_ctx = avcodec_alloc_context3(decoder);
    if (!decoder_ctx) {
        fprintf(stderr, "Failed to allocate decoder context\n");
        goto end;
    }

    // copy codec parameters to decoder context
    if ((ret = avcodec_parameters_to_context(decoder_ctx, input_ctx->streams[video_stream_index]->codecpar)) < 0) {
        fprintf(stderr, "Failed to copy codec parameters to decoder context: %s\n", av_err2str(ret));
        goto end;
    }

    // open decoder
    if ((ret = avcodec_open2(decoder_ctx, decoder, NULL)) < 0) {
        fprintf(stderr, "Failed to open decoder: %s\n", av_err2str(ret));
        goto end;
    }

    // allocate encoder context
    encoder = avcodec_find_encoder(AV_CODEC_ID_MPEG4);
    if (!encoder) {
        fprintf(stderr, "Failed to find encoder\n");
        goto end;
    }

    encoder_ctx = avcodec_alloc_context3(encoder);
    if (!encoder_ctx) {
        fprintf(stderr, "Failed to allocate encoder context\n");
        goto end;
    }

    // set encoder parameters
    encoder_ctx->bit_rate = 400000;
    encoder_ctx->width = decoder_ctx->width;
    encoder_ctx->height = decoder_ctx->height;
    encoder_ctx->time_base = decoder_ctx->time_base;
    encoder_ctx->framerate = decoder_ctx->framerate;
    encoder_ctx->gop_size = 10;
    encoder_ctx->max_b_frames = 1;
    encoder_ctx->pix_fmt = AV_PIX_FMT_YUV420P;

    // open encoder
    if ((ret = avcodec_open2(encoder_ctx, encoder, NULL)) < 0) {
        fprintf(stderr, "Failed to open encoder: %s\n", av_err2str(ret));
        goto end;
    }

    // allocate frame
    frame = av_frame_alloc();
    if (!frame) {
        fprintf(stderr, "Failed to allocate frame\n");
        goto end;
    }

    // allocate temporary frame
    tmp_frame = av_frame_alloc();
    if (!tmp_frame) {
        fprintf(stderr, "Failed to allocate temporary frame\n");
        goto end;
    }

    // allocate packet
    pkt = av_packet_alloc();
    if (!pkt) {
        fprintf(stderr, "Failed to allocate packet\n");
        goto end;
    }

    // open output file
    if ((ret = avformat_alloc_output_context2(&output_ctx, NULL, NULL, output_file)) < 0) {
        fprintf(stderr, "Failed to allocate output context: %s\n", av_err2str(ret));
        goto end;
    }

    // add video stream to output context
    AVStream *out_stream = avformat_new_stream(output_ctx, NULL);
    if (!out_stream) {
        fprintf(stderr, "Failed to allocate output stream\n");
        goto end;
    }

    // copy codec parameters from encoder context to output stream
    if ((ret = avcodec_parameters_from_context(out_stream->codecpar, encoder_ctx)) < 0) {
        fprintf(stderr, "Failed to copy codec parameters from encoder context to output stream: %s\n", av_err2str(ret));
        goto end;
    }

    // set time base for output stream
    out_stream->time_base = encoder_ctx->time_base;

    // write header to output file
    if ((ret = avformat_write_header(output_ctx, NULL)) < 0) {
        fprintf(stderr, "Failed to write header to output file: %s\n", av_err2str(ret));
        goto end;
    }

    // read packets from input file, decode them, and encode them to output file
    while (av_read_frame(input_ctx, pkt) >= 0) {
        if (pkt->stream_index != video_stream_index) {
            av_packet_unref(pkt);
            continue;
        }

        // decode packet
        len = avcodec_send_packet(decoder_ctx, pkt);
        if (len < 0) {
            fprintf(stderr, "Failed to decode packet: %s\n", av_err2str(len));
            goto end;
        }

        while (len >= 0) {
            // get decoded frame
            len = avcodec_receive_frame(decoder_ctx, tmp_frame);
            if (len == AVERROR(EAGAIN) || len == AVERROR_EOF) {
                break;
            } else if (len < 0) {
                fprintf(stderr, "Failed to receive decoded frame: %s\n", av_err2str(len));
                goto end;
            }

            // convert frame to output format
            if (tmp_frame->format != encoder_ctx->pix_fmt || tmp_frame->width != encoder_ctx->width || tmp_frame->height != encoder_ctx->height) {
                if (frame) {
                    av_frame_free(&frame);
                }

                frame = av_frame_alloc();
                if (!frame) {
                    fprintf(stderr, "Failed to allocate frame\n");
                    goto end;
                }

                frame->format = encoder_ctx->pix_fmt;
                frame->width = encoder_ctx->width;
                frame->height = encoder_ctx->height;

                if ((ret = av_frame_get_buffer(frame, 32)) < 0) {
                    fprintf(stderr, "Failed to allocate frame buffer: %s\n", av_err2str(ret));
                    goto end;
                }

                // convert frame
                struct SwsContext *sws_ctx = sws_getContext(tmp_frame->width, tmp_frame->height, (enum AVPixelFormat)tmp_frame->format,
                                                            encoder_ctx->width, encoder_ctx->height, encoder_ctx->pix_fmt,
                                                            SWS_BILINEAR, NULL, NULL, NULL);
                if (!sws_ctx) {
                    fprintf(stderr, "Failed to allocate SwsContext\n");
                    goto end;
                }

                sws_scale(sws_ctx, tmp_frame->data, tmp_frame->linesize, 0, tmp_frame->height, frame->data, frame->linesize);
                sws_freeContext(sws_ctx);
            } else {
                frame = tmp_frame;
                tmp_frame = NULL;
            }

            // encode frame
            len = avcodec_send_frame(encoder_ctx, frame);
            if (len < 0) {
                fprintf(stderr, "Failed to encode frame: %s\n", av_err2str(len));
                goto end;
            }

            while (len >= 0) {
                // get encoded packet
                len = avcodec_receive_packet(encoder_ctx, pkt);
                if (len == AVERROR(EAGAIN) || len == AVERROR_EOF) {
                    break;
                } else if (len < 0) {
                    fprintf(stderr, "Failed to receive encoded packet: %s\n", av_err2str(len));
                    goto end;
                }

                // write packet to output file
                if ((ret = av_write_frame(output_ctx, pkt)) < 0) {
                    fprintf(stderr, "Failed to write packet to output file: %s\n", av_err2str(ret));
                    goto end;
                }

                av_packet_unref(pkt);
            }
        }

        av_packet_unref(pkt);
    }

    // flush encoder
    if ((ret = avcodec_send_frame(encoder_ctx, NULL)) < 0) {
        fprintf(stderr, "Failed to flush encoder: %s\n", av_err2str(ret));
        goto end;
    }

    while (ret >= 0) {
        ret = avcodec_receive_packet(encoder_ctx, pkt);
        if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
            break;
        } else if (ret < 0) {
            fprintf(stderr, "Failed to receive encoded packet: %s\n", av_err2str(ret));
            goto end;
        }

        // write packet to output file
        if ((ret = av_write_frame(output_ctx, pkt)) < 0) {
            fprintf(stderr, "Failed to write packet to output file: %s\n", av_err2str(ret));
            goto end;
        }

        av_packet_unref(pkt);
    }

    // write trailer to output file
    if ((ret = av_write_trailer(output_ctx)) < 0) {
        fprintf(stderr, "Failed to write trailer to output file: %s\n", av_err2str(ret));
        goto end;
    }

    printf("Finished converting %s to %s\n", input_file, output_file);

end:
    if (input_ctx) {
        avformat_close_input(&input_ctx);
    }

    if (output_ctx) {
        avio_closep(&output_ctx->pb);
        avformat_free_context(output_ctx);
    }

    if (decoder_ctx) {
        avcodec_free_context(&decoder_ctx);
    }

    if (encoder_ctx) {
        avcodec_free_context(&encoder_ctx);
    }

    if (frame) {
        av_frame_free(&frame);
    }

    if (tmp_frame) {
        av_frame_free(&tmp_frame);
    }

    if (pkt) {
        av_packet_free(&pkt);
    }

    return ret < 0;
}

此程序使用了FFmpeg的AVFormatContext、AVCodecContext、AVCodec、AVFrame、AVPacket和SwsContext等结构体/函数。使用VS Code编写C代码时，需要配置好FFmpeg的库文件和头文件路径。可以在VS Code的tasks.json文件中添加以下代码：

{
    "label": "build",
    "type": "shell",
    "command": "gcc",
    "args": [
        "-g",
        "-o",
        "${fileDirname}\\${fileBasenameNoExtension}.exe",
        "${file}",
        "-lavcodec",
        "-lavformat",
        "-lavutil",
        "-lswscale",
        "-lmingw32",
        "-lSDL2main",
        "-lSDL2",
        "-I${workspaceFolder}\\include",
        "-L${workspaceFolder}\\lib",
        "-Wl,-Bstatic",
        "-lstdc++",
        "-lpng",
        "-lz",
        "-lm",
        "-Wl,-Bdynamic",
        "-lwinmm",
        "-lole32",
        "-loleaut32",
        "-luuid",
        "-lcomctl32",
        "-lcomdlg32"
    ],
    "options": {
        "cwd": "${workspaceFolder}"
    },
    "problemMatcher": {
        "owner": "cpp",
        "fileLocation": ["relative", "${workspaceFolder}"],
        "pattern": {
            "regexp": "^(.*):(\\\\d+):(\\\\d+):\\s+(warning|error):\\s+(.*)$",
            "file": 1,
            "line": 2,
            "column": 3,
            "severity": 4,
            "message": 5
        }
    }
}

此处假设你的FFmpeg库文件和头文件保存在VS Code工作区的lib和include文件夹中。你需要根据实际情况修改这些路径。然后，你可以使用Ctrl+Shift+B命令来编译和运行程序。

dav转mp4用ffmpeg的cpp代码 visual studio

以下是使用FFmpeg进行dav转mp4的cpp代码（在Visual Studio环境下）：

extern "C" {
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavutil/avutil.h>
#include <libavutil/dict.h>
#include <libavutil/error.h>
#include <libavutil/mathematics.h>
#include <libavutil/opt.h>
#include <libavutil/samplefmt.h>
#include <libswscale/swscale.h>
}

int main()
{
    const char* input_file_path = "input.dav";
    const char* output_file_path = "output.mp4";

    // Open input file
    AVFormatContext* format_ctx = nullptr;

    if (avformat_open_input(&format_ctx, input_file_path, nullptr, nullptr) < 0) {
        av_log(nullptr, AV_LOG_ERROR, "Could not open input file %s\n", input_file_path);
        return -1;
    }

    // Get stream info
    if (avformat_find_stream_info(format_ctx, nullptr) < 0) {
        av_log(nullptr, AV_LOG_ERROR, "Could not find stream information\n");
        return -1;
    }

    // Find video and audio stream
    AVCodec* video_codec = nullptr;
    AVCodec* audio_codec = nullptr;
    int video_stream_index = -1;
    int audio_stream_index = -1;

    for (int i = 0; i < format_ctx->nb_streams; ++i) {
        if (format_ctx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
            video_stream_index = i;
            video_codec = avcodec_find_decoder(format_ctx->streams[i]->codecpar->codec_id);
        }
        else if (format_ctx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
            audio_stream_index = i;
            audio_codec = avcodec_find_decoder(format_ctx->streams[i]->codecpar->codec_id);
        }
    }

    if (video_stream_index == -1 && audio_stream_index == -1) {
        av_log(nullptr, AV_LOG_ERROR, "Could not find any video or audio stream\n");
        return -1;
    }

    // Open video codec
    AVCodecContext* video_codec_ctx = nullptr;

    if (video_codec != nullptr) {
        video_codec_ctx = avcodec_alloc_context3(video_codec);

        if (avcodec_parameters_to_context(video_codec_ctx, format_ctx->streams[video_stream_index]->codecpar) < 0) {
            av_log(nullptr, AV_LOG_ERROR, "Could not copy video codec parameters to context\n");
            return -1;
        }

        if (avcodec_open2(video_codec_ctx, video_codec, nullptr) < 0) {
            av_log(nullptr, AV_LOG_ERROR, "Could not open video codec\n");
            return -1;
        }
    }

    // Open audio codec
    AVCodecContext* audio_codec_ctx = nullptr;

    if (audio_codec != nullptr) {
        audio_codec_ctx = avcodec_alloc_context3(audio_codec);

        if (avcodec_parameters_to_context(audio_codec_ctx, format_ctx->streams[audio_stream_index]->codecpar) < 0) {
            av_log(nullptr, AV_LOG_ERROR, "Could not copy audio codec parameters to context\n");
            return -1;
        }

        if (avcodec_open2(audio_codec_ctx, audio_codec, nullptr) < 0) {
            av_log(nullptr, AV_LOG_ERROR, "Could not open audio codec\n");
            return -1;
        }
    }

    // Open output file
    AVFormatContext* output_format_ctx = nullptr;

    if (avformat_alloc_output_context2(&output_format_ctx, nullptr, nullptr, output_file_path) < 0) {
        av_log(nullptr, AV_LOG_ERROR, "Could not create output context\n");
        return -1;
    }

    // Add video stream to output file
    AVStream* video_stream = nullptr;

    if (video_codec_ctx != nullptr) {
        video_stream = avformat_new_stream(output_format_ctx, video_codec);
        if (video_stream == nullptr) {
            av_log(nullptr, AV_LOG_ERROR, "Could not create video stream\n");
            return -1;
        }

        if (avcodec_parameters_copy(video_stream->codecpar, format_ctx->streams[video_stream_index]->codecpar) < 0) {
            av_log(nullptr, AV_LOG_ERROR, "Could not copy video codec parameters to output stream\n");
            return -1;
        }

        if (avcodec_parameters_to_context(video_stream->codec, video_stream->codecpar) < 0) {
            av_log(nullptr, AV_LOG_ERROR, "Could not copy video codec parameters to output stream context\n");
            return -1;
        }

        video_stream->codec->codec_tag = 0;
        video_stream->time_base = format_ctx->streams[video_stream_index]->time_base;
    }

    // Add audio stream to output file
    AVStream* audio_stream = nullptr;

    if (audio_codec_ctx != nullptr) {
        audio_stream = avformat_new_stream(output_format_ctx, audio_codec);
        if (audio_stream == nullptr) {
            av_log(nullptr, AV_LOG_ERROR, "Could not create audio stream\n");
            return -1;
        }

        if (avcodec_parameters_copy(audio_stream->codecpar, format_ctx->streams[audio_stream_index]->codecpar) < 0) {
            av_log(nullptr, AV_LOG_ERROR, "Could not copy audio codec parameters to output stream\n");
            return -1;
        }

        if (avcodec_parameters_to_context(audio_stream->codec, audio_stream->codecpar) < 0) {
            av_log(nullptr, AV_LOG_ERROR, "Could not copy audio codec parameters to output stream context\n");
            return -1;
        }

        audio_stream->codec->codec_tag = 0;
        audio_stream->time_base = format_ctx->streams[audio_stream_index]->time_base;
    }

    // Open output file for writing
    if (!(output_format_ctx->oformat->flags & AVFMT_NOFILE)) {
        if (avio_open(&output_format_ctx->pb, output_file_path, AVIO_FLAG_WRITE) < 0) {
            av_log(nullptr, AV_LOG_ERROR, "Could not open output file %s\n", output_file_path);
            return -1;
        }
    }

    // Write header to output file
    if (avformat_write_header(output_format_ctx, nullptr) < 0) {
        av_log(nullptr, AV_LOG_ERROR, "Could not write header to output file\n");
        return -1;
    }

    // Convert video frames
    AVFrame* video_frame = av_frame_alloc();
    AVFrame* video_frame_rgb = av_frame_alloc();

    if (video_codec_ctx != nullptr) {
        SwsContext* sws_ctx = sws_getContext(video_codec_ctx->width, video_codec_ctx->height,
            video_codec_ctx->pix_fmt, video_codec_ctx->width, video_codec_ctx->height,
            AV_PIX_FMT_RGB24, SWS_BILINEAR, nullptr, nullptr, nullptr);

        if (sws_ctx == nullptr) {
            av_log(nullptr, AV_LOG_ERROR, "Could not create SwsContext\n");
            return -1;
        }

        av_image_alloc(video_frame_rgb->data, video_frame_rgb->linesize, video_codec_ctx->width, video_codec_ctx->height,
            AV_PIX_FMT_RGB24, 1);

        AVPacket packet;
        av_init_packet(&packet);

        while (av_read_frame(format_ctx, &packet) >= 0) {
            if (packet.stream_index == video_stream_index) {
                if (avcodec_send_packet(video_codec_ctx, &packet) == 0) {
                    while (avcodec_receive_frame(video_codec_ctx, video_frame) == 0) {
                        sws_scale(sws_ctx, video_frame->data, video_frame->linesize, 0,
                            video_codec_ctx->height, video_frame_rgb->data, video_frame_rgb->linesize);

                        video_frame_rgb->pts = video_frame->pts;

                        if (avcodec_send_frame(video_stream->codec, video_frame_rgb) < 0) {
                            av_log(nullptr, AV_LOG_ERROR, "Could not send video frame to output stream\n");
                            return -1;
                        }

                        while (avcodec_receive_packet(video_stream->codec, &packet) == 0) {
                            if (av_write_frame(output_format_ctx, &packet) < 0) {
                                av_log(nullptr, AV_LOG_ERROR, "Could not write video packet to output file\n");
                                return -1;
                            }

                            av_packet_unref(&packet);
                        }
                    }
                }
            }

            av_packet_unref(&packet);
        }

        avcodec_send_frame(video_stream->codec, nullptr);

        while (avcodec_receive_packet(video_stream->codec, &packet) == 0) {
            if (av_write_frame(output_format_ctx, &packet) < 0) {
                av_log(nullptr, AV_LOG_ERROR, "Could not write video packet to output file\n");
                return -1;
            }

            av_packet_unref(&packet);
        }

        sws_freeContext(sws_ctx);
    }

    // Convert audio frames
    AVFrame* audio_frame = av_frame_alloc();

    if (audio_codec_ctx != nullptr) {
        AVPacket packet;
        av_init_packet(&packet);

        while (av_read_frame(format_ctx, &packet) >= 0) {
            if (packet.stream_index == audio_stream_index) {
                if (avcodec_send_packet(audio_codec_ctx, &packet) == 0) {
                    while (avcodec_receive_frame(audio_codec_ctx, audio_frame) == 0) {
                        audio_frame->pts = audio_frame->best_effort_timestamp;

                        if (avcodec_send_frame(audio_stream->codec, audio_frame) < 0) {
                            av_log(nullptr, AV_LOG_ERROR, "Could not send audio frame to output stream\n");
                            return -1;
                        }

                        while (avcodec_receive_packet(audio_stream->codec, &packet) == 0) {
                            if (av_write_frame(output_format_ctx, &packet) < 0) {
                                av_log(nullptr, AV_LOG_ERROR, "Could not write audio packet to output file\n");
                                return -1;
                            }

                            av_packet_unref(&packet);
                        }
                    }
                }
            }

            av_packet_unref(&packet);
        }

        avcodec_send_frame(audio_stream->codec, nullptr);

        while (avcodec_receive_packet(audio_stream->codec, &packet) == 0) {
            if (av_write_frame(output_format_ctx, &packet) < 0) {
                av_log(nullptr, AV_LOG_ERROR, "Could not write audio packet to output file\n");
                return -1;
            }

            av_packet_unref(&packet);
        }
    }

    // Write trailer to output file
    if (av_write_trailer(output_format_ctx) < 0) {
        av_log(nullptr, AV_LOG_ERROR, "Could not write trailer to output file\n");
        return -1;
    }

    // Close output file
    if (!(output_format_ctx->oformat->flags & AVFMT_NOFILE)) {
        avio_close(output_format_ctx->pb);
    }

    // Free resources
    avcodec_free_context(&video_codec_ctx);
    avcodec_free_context(&audio_codec_ctx);
    avformat_close_input(&format_ctx);
    avformat_free_context(output_format_ctx);
    av_frame_free(&video_frame);
    av_frame_free(&video_frame_rgb);
    av_frame_free(&audio_frame);

    return 0;
}

这段代码使用了FFmpeg的多个库来进行视频和音频的解码、转换和编码，具体实现细节可以参考FFmpeg的官方文档。