这是基于FFMPEG的视频编码器,可以将yuv视频元数据编码成h264压缩编码数据。
主要是记录一下自己学习FFMPEG时总结的视频编码流程。
ffmpeg版本:ffmpeg-4.2.2
libx264版本:x264-snapshot-20191023-2245-stable
avcodec_find_encoder_by_name():通过编码器的名字查找编码器
avcodec_alloc_context3():初始化AVCodecContext
avcodec_open2():打开编码器
av_packet_alloc():初始化AVPacket
av_frame_alloc():初始化AVFrame
av_frame_get_buffer():为AVFrame->data等分配内存
av_frame_make_writable():检查AVFrame->data是否可写
avcodec_send_frame():编码视频:将一帧视频元数据发送给编码器
avcodec_receive_packet():编码视频:接收编码完成的AVPacket数据包
#include
#include
#include
#include
#include
#include
static void encode(AVCodecContext *cdc_ctx, AVFrame *frame, AVPacket *pkt, FILE *fp_out)
{
int ret = 0;
if (frame != NULL)
printf("Send %d frame.\n", frame->pts);
if ((ret = avcodec_send_frame(cdc_ctx, frame)) < 0)
{
fprintf(stderr, "avcodec_send_frame failed.\n");
exit(1);
}
while ((ret = avcodec_receive_packet(cdc_ctx, pkt)) >= 0)
{
printf("Write %d packet.\n", pkt->pts);
fwrite(pkt->data, 1, pkt->size, fp_out);
av_packet_unref(pkt);
}
if ((ret != AVERROR(EAGAIN)) && (ret != AVERROR_EOF))
{
fprintf(stderr, "avcodec_receive_packet failed.\n");
exit(1);
}
}
void encode_video(const char *input_file, const char *output_file, const char *encoder_name)
{
int ret = 0;
int i = 0;
AVCodec *codec = NULL;
AVCodecContext *cdc_ctx = NULL;
AVPacket *pkt = NULL;
AVFrame *frame = NULL;
FILE *fp_in, *fp_out;
if ((codec = avcodec_find_encoder_by_name(encoder_name)) == NULL)
{
fprintf(stderr, "avcodec_find_encoder_by_name failed.\n");
goto ret1;
}
if ((cdc_ctx = avcodec_alloc_context3(codec)) == NULL)
{
fprintf(stderr, "avcodec_alloc_context3 failed.\n");
goto ret1;
}
cdc_ctx->bit_rate = 400000;
cdc_ctx->width = 352;
cdc_ctx->height = 288;
cdc_ctx->time_base = (AVRational){1,25};
cdc_ctx->framerate = (AVRational){25,1};
cdc_ctx->gop_size = 10;
cdc_ctx->max_b_frames = 1;
cdc_ctx->pix_fmt = AV_PIX_FMT_YUV420P;
if (codec->id == AV_CODEC_ID_H264)
av_opt_set(cdc_ctx->priv_data, "preset", "slow", 0);
if ((ret = avcodec_open2(cdc_ctx, codec, NULL)) < 0)
{
fprintf(stderr, "avcodec_open2 failed.\n");
goto ret2;
}
if ((pkt = av_packet_alloc()) == NULL)
{
fprintf(stderr, "av_packet_alloc failed.\n");
goto ret3;
}
if ((frame = av_frame_alloc()) == NULL)
{
fprintf(stderr, "av_frame_alloc failed.\n");
goto ret4;
}
frame->format = cdc_ctx->pix_fmt;
frame->width = cdc_ctx->width;
frame->height = cdc_ctx->height;
if ((ret = av_frame_get_buffer(frame, 0)) < 0)
{
fprintf(stderr, "av_frame_get_buffer failed.\n");
goto ret5;
}
if ((fp_in = fopen(input_file, "rb")) == NULL)
{
fprintf(stderr, "fopen %s failed.\n", input_file);
goto ret5;
}
if ((fp_out = fopen(output_file, "wb")) == NULL)
{
fprintf(stderr, "fopen %s failed.\n", output_file);
goto ret6;
}
while (feof(fp_in) == 0)
{
int y = 0;
if ((ret = av_frame_make_writable(frame)) < 0)
{
fprintf(stderr, "frame is not writable.\n");
goto ret7;
}
/*y*/
for (y = 0; y < frame->height; y++)
fread(&frame->data[0][y * frame->linesize[0]], 1, frame->width, fp_in);
/*u*/
for (y = 0; y < frame->height / 2; y++)
fread(&frame->data[1][y * frame->linesize[1]], 1, frame->width / 2, fp_in);
/*v*/
for (y = 0; y < frame->height / 2; y++)
fread(&frame->data[2][y * frame->linesize[2]], 1, frame->width / 2, fp_in);
frame->pts = i++;
encode(cdc_ctx, frame, pkt, fp_out);
}
/*flush buffer*/
encode(cdc_ctx, NULL, pkt, fp_out);
fclose(fp_out);
fclose(fp_in);
av_frame_free(&frame);
av_packet_free(&pkt);
avcodec_close(cdc_ctx);
avcodec_free_context(&cdc_ctx);
return;
ret7:
fclose(fp_out);
ret6:
fclose(fp_in);
ret5:
av_frame_free(&frame);
ret4:
av_packet_free(&pkt);
ret3:
avcodec_close(cdc_ctx);
ret2:
avcodec_free_context(&cdc_ctx);
ret1:
exit(1);
}
int main(int argc, const char *argv[])
{
if (argc < 4)
{
fprintf(stderr, "Uage: );
exit(0);
}
encode_video(argv[1], argv[2], argv[3]);
return 0;
}
注:
Github:https://github.com/newbie-plan/encode_video