C语言怎么获取ffmpeg的api
时间: 2023-05-29 16:03:57 浏览: 61
获取FFmpeg的API,需要进行以下步骤:
1. 下载FFmpeg源代码,可以从官方网站(https://ffmpeg.org/download.html)下载最新版本的源代码。
2. 安装FFmpeg,可以按照官方文档(https://ffmpeg.org/documentation.html)进行安装。
3. 在C语言代码中包含FFmpeg的头文件,例如:
#include <libavformat/avformat.h>
4. 在C语言代码中调用FFmpeg的API函数,例如:
AVFormatContext *avFormatContext = avformat_alloc_context();
int ret = avformat_open_input(&avFormatContext, "input.mp4", NULL, NULL);
if (ret < 0) {
printf("Could not open input file.\n");
return -1;
}
5. 编译C语言代码时需要链接FFmpeg的库文件,例如:
gcc -o myapp myapp.c -lavformat -lavcodec -lavutil
其中-lavformat、-lavcodec、-lavutil是链接FFmpeg的库文件。
以上就是获取FFmpeg的API的步骤。
相关问题
用C语言调用ffmpeg的api
以下是一些基本的C语言代码,用于调用FFmpeg API:
```c
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavutil/imgutils.h>
#include <libswscale/swscale.h>
int main(int argc, char *argv[]) {
AVFormatContext *format_ctx = NULL;
AVCodecContext *codec_ctx = NULL;
AVCodec *codec = NULL;
AVFrame *frame = NULL;
AVPacket packet;
struct SwsContext *sws_ctx = NULL;
// Open video file
if (avformat_open_input(&format_ctx, "input.mp4", NULL, NULL) != 0) {
fprintf(stderr, "Error: Could not open video file\n");
return -1;
}
// Retrieve stream information
if (avformat_find_stream_info(format_ctx, NULL) < 0) {
fprintf(stderr, "Error: Could not retrieve stream information\n");
return -1;
}
// Find video stream
int video_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;
break;
}
}
if (video_stream_index == -1) {
fprintf(stderr, "Error: Could not find video stream\n");
return -1;
}
// Get video codec
codec = avcodec_find_decoder(format_ctx->streams[video_stream_index]->codecpar->codec_id);
if (codec == NULL) {
fprintf(stderr, "Error: Could not find video codec\n");
return -1;
}
// Allocate codec context
codec_ctx = avcodec_alloc_context3(codec);
if (codec_ctx == NULL) {
fprintf(stderr, "Error: Could not allocate codec context\n");
return -1;
}
// Copy codec parameters to codec context
if (avcodec_parameters_to_context(codec_ctx, format_ctx->streams[video_stream_index]->codecpar) < 0) {
fprintf(stderr, "Error: Could not copy codec parameters to codec context\n");
return -1;
}
// Open codec
if (avcodec_open2(codec_ctx, codec, NULL) < 0) {
fprintf(stderr, "Error: Could not open codec\n");
return -1;
}
// Allocate frame
frame = av_frame_alloc();
if (frame == NULL) {
fprintf(stderr, "Error: Could not allocate frame\n");
return -1;
}
// Allocate packet
av_init_packet(&packet);
// Initialize scaler
sws_ctx = sws_getContext(codec_ctx->width, codec_ctx->height, codec_ctx->pix_fmt,
codec_ctx->width, codec_ctx->height, AV_PIX_FMT_RGB24,
SWS_BILINEAR, NULL, NULL, NULL);
if (sws_ctx == NULL) {
fprintf(stderr, "Error: Could not initialize scaler\n");
return -1;
}
// Read frames from video file
while (av_read_frame(format_ctx, &packet) >= 0) {
if (packet.stream_index == video_stream_index) {
// Decode video frame
int ret = avcodec_send_packet(codec_ctx, &packet);
if (ret < 0) {
fprintf(stderr, "Error: Could not send packet for decoding\n");
return -1;
}
while (ret >= 0) {
ret = avcodec_receive_frame(codec_ctx, frame);
if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
break;
} else if (ret < 0) {
fprintf(stderr, "Error: Could not decode video frame\n");
return -1;
}
// Convert pixel format
uint8_t *data[1] = {NULL};
data[0] = (uint8_t *) frame->data[0];
int linesize[1] = {0};
linesize[0] = frame->linesize[0];
sws_scale(sws_ctx, data, linesize, 0, codec_ctx->height,
frame->data, frame->linesize);
// Process video frame
// ...
}
}
// Free packet
av_packet_unref(&packet);
}
// Free scaler context
sws_freeContext(sws_ctx);
// Free frame
av_frame_free(&frame);
// Close codec
avcodec_close(codec_ctx);
// Free codec context
avcodec_free_context(&codec_ctx);
// Close video file
avformat_close_input(&format_ctx);
return 0;
}
```
这个代码段演示了如何打开视频文件,检索流信息,找到视频流,获取视频编解码器,分配编解码器上下文,打开编解码器,分配帧,初始化包,初始化缩放器,从视频文件中读取帧,解码帧,转换像素格式,处理帧,释放资源并关闭视频文件。这是一个基本的例子,可以根据需要进行修改和扩展。
用C语言调用ffmpeg的api读取文件的像素数据
以下是使用C语言调用FFmpeg的API读取文件的像素数据的示例代码:
```c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <libavutil/imgutils.h>
#include <libavutil/parseutils.h>
#include <libavformat/avformat.h>
int main(int argc, char **argv)
{
AVFormatContext *fmt_ctx = NULL;
int video_stream_index = -1;
AVCodecParameters *codec_params = NULL;
AVCodec *decoder = NULL;
AVCodecContext *decoder_ctx = NULL;
AVFrame *frame = NULL;
int ret, i;
if (argc < 2) {
fprintf(stderr, "Usage: %s <input_file>\n", argv[0]);
return 1;
}
// Open input file
ret = avformat_open_input(&fmt_ctx, argv[1], NULL, NULL);
if (ret < 0) {
fprintf(stderr, "Failed to open input file: %s\n", av_err2str(ret));
goto end;
}
// Read stream information
ret = avformat_find_stream_info(fmt_ctx, NULL);
if (ret < 0) {
fprintf(stderr, "Failed to read stream information: %s\n", av_err2str(ret));
goto end;
}
// Find video stream
for (i = 0; i < fmt_ctx->nb_streams; i++) {
if (fmt_ctx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
video_stream_index = i;
break;
}
}
if (video_stream_index == -1) {
fprintf(stderr, "No video stream found in input file\n");
goto end;
}
// Get codec parameters
codec_params = fmt_ctx->streams[video_stream_index]->codecpar;
// Find decoder
decoder = avcodec_find_decoder(codec_params->codec_id);
if (!decoder) {
fprintf(stderr, "Failed to find decoder for codec ID %d\n", codec_params->codec_id);
goto end;
}
// Allocate decoder context
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
ret = avcodec_parameters_to_context(decoder_ctx, codec_params);
if (ret < 0) {
fprintf(stderr, "Failed to copy codec parameters to decoder context: %s\n", av_err2str(ret));
goto end;
}
// Open decoder
ret = avcodec_open2(decoder_ctx, decoder, NULL);
if (ret < 0) {
fprintf(stderr, "Failed to open decoder: %s\n", av_err2str(ret));
goto end;
}
// Allocate frame
frame = av_frame_alloc();
if (!frame) {
fprintf(stderr, "Failed to allocate frame\n");
goto end;
}
// Read frames from input file
while (1) {
AVPacket pkt = {0};
av_init_packet(&pkt);
ret = av_read_frame(fmt_ctx, &pkt);
if (ret == AVERROR_EOF)
break;
if (ret < 0) {
fprintf(stderr, "Failed to read frame: %s\n", av_err2str(ret));
goto end;
}
// Decode packet
ret = avcodec_send_packet(decoder_ctx, &pkt);
if (ret < 0) {
fprintf(stderr, "Failed to send packet to decoder: %s\n", av_err2str(ret));
goto end;
}
while (ret >= 0) {
ret = avcodec_receive_frame(decoder_ctx, frame);
if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
break;
if (ret < 0) {
fprintf(stderr, "Failed to receive frame from decoder: %s\n", av_err2str(ret));
goto end;
}
// Process frame
printf("Frame %d (type=%c, size=%d bytes) pts %d key_frame %d\n",
decoder_ctx->frame_number, av_get_picture_type_char(frame->pict_type),
frame->pkt_size, frame->pts, frame->key_frame);
// Process pixel data
uint8_t *data[AV_NUM_DATA_POINTERS] = {0};
int linesize[AV_NUM_DATA_POINTERS] = {0};
int width, height;
data[0] = frame->data[0];
linesize[0] = frame->linesize[0];
width = frame->width;
height = frame->height;
// Process Y component
for (i = 0; i < height; i++) {
fwrite(data[0] + i * linesize[0], 1, width, stdout);
}
// Process U component
if (codec_params->format == AV_PIX_FMT_YUV420P) {
data[1] = frame->data[1];
linesize[1] = frame->linesize[1];
for (i = 0; i < height/2; i++) {
fwrite(data[1] + i * linesize[1], 1, width/2, stdout);
}
}
// Process V component
if (codec_params->format == AV_PIX_FMT_YUV420P) {
data[2] = frame->data[2];
linesize[2] = frame->linesize[2];
for (i = 0; i < height/2; i++) {
fwrite(data[2] + i * linesize[2], 1, width/2, stdout);
}
}
printf("\n");
av_frame_unref(frame);
}
av_packet_unref(&pkt);
}
end:
if (frame)
av_frame_free(&frame);
if (decoder_ctx)
avcodec_free_context(&decoder_ctx);
if (fmt_ctx)
avformat_close_input(&fmt_ctx);
return ret;
}
```
此代码可读取输入文件中的视频帧,然后处理像素数据并将其写入stdout。在处理像素数据时,该代码将Y、U和V分量分别写入stdout。在处理像素数据时,还应注意缩放、旋转和其他处理,以使像素数据适合应用程序的需要。