问题描述
我正在开发H265编码软件,在单元测试中,我遇到了一些奇怪的内存泄漏。为了找到它们,我修改了FFMPEG documentation中的encode_video.c
示例。我更改了分辨率以对应4K视频,调整了比特率,并在上下文分配之前添加了一个暂停,在最终返回之前添加了一个暂停:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <libavcodec/avcodec.h>
#include <libavutil/opt.h>
#include <libavutil/imgutils.h>
static void encode(AVCodecContext *enc_ctx,AVFrame *frame,AVPacket *pkt,FILE *outfile)
{
int ret;
/* send the frame to the encoder */
if (frame)
printf("Send frame %3"PRId64"\n",frame->pts);
ret = avcodec_send_frame(enc_ctx,frame);
if (ret < 0) {
fprintf(stderr,"Error sending a frame for encoding\n");
exit(1);
}
while (ret >= 0) {
ret = avcodec_receive_packet(enc_ctx,pkt);
if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
return;
else if (ret < 0) {
fprintf(stderr,"Error during encoding\n");
exit(1);
}
printf("Write packet %3"PRId64" (size=%5d)\n",pkt->pts,pkt->size);
fwrite(pkt->data,1,pkt->size,outfile);
av_packet_unref(pkt);
}
}
int main(int argc,char **argv)
{
const char *filename,*codec_name;
const AVCodec *codec;
AVCodecContext *c= NULL;
int i,ret,x,y;
FILE *f;
AVFrame *frame;
AVPacket *pkt;
uint8_t endcode[] = { 0,0xb7 };
if (argc <= 2) {
fprintf(stderr,"Usage: %s <output file> <codec name>\n",argv[0]);
exit(0);
}
filename = argv[1];
codec_name = argv[2];
sleep(10);
/* find the mpeg1video encoder */
codec = avcodec_find_encoder_by_name(codec_name);
if (!codec) {
fprintf(stderr,"Codec '%s' not found\n",codec_name);
exit(1);
}
c = avcodec_alloc_context3(codec);
if (!c) {
fprintf(stderr,"Could not allocate video codec context\n");
exit(1);
}
pkt = av_packet_alloc();
if (!pkt)
exit(1);
/* put sample parameters */
c->bit_rate = 1000000;
/* resolution must be a multiple of two */
c->width = 3840;
c->height = 2160;
/* frames per second */
c->time_base = (AVRational){1,25};
c->framerate = (AVRational){25,1};
/* emit one intra frame every ten frames
* check frame pict_type before passing frame
* to encoder,if frame->pict_type is AV_PICTURE_TYPE_I
* then gop_size is ignored and the output of encoder
* will always be I frame irrespective to gop_size
*/
c->gop_size = 10;
c->max_b_frames = 1;
c->pix_fmt = AV_PIX_FMT_YUV420P;
if (codec->id == AV_CODEC_ID_H264)
av_opt_set(c->priv_data,"preset","slow",0);
/* open it */
ret = avcodec_open2(c,codec,NULL);
if (ret < 0) {
fprintf(stderr,"Could not open codec: %s\n",av_err2str(ret));
exit(1);
}
f = fopen(filename,"wb");
if (!f) {
fprintf(stderr,"Could not open %s\n",filename);
exit(1);
}
frame = av_frame_alloc();
if (!frame) {
fprintf(stderr,"Could not allocate video frame\n");
exit(1);
}
frame->format = c->pix_fmt;
frame->width = c->width;
frame->height = c->height;
ret = av_frame_get_buffer(frame,0);
if (ret < 0) {
fprintf(stderr,"Could not allocate the video frame data\n");
exit(1);
}
/* encode 1 second of video */
for (i = 0; i < 25; i++) {
fflush(stdout);
/* make sure the frame data is writable */
ret = av_frame_make_writable(frame);
if (ret < 0)
exit(1);
/* prepare a dummy image */
/* Y */
for (y = 0; y < c->height; y++) {
for (x = 0; x < c->width; x++) {
frame->data[0][y * frame->linesize[0] + x] = x + y + i * 3;
}
}
/* Cb and Cr */
for (y = 0; y < c->height/2; y++) {
for (x = 0; x < c->width/2; x++) {
frame->data[1][y * frame->linesize[1] + x] = 128 + y + i * 2;
frame->data[2][y * frame->linesize[2] + x] = 64 + x + i * 5;
}
}
frame->pts = i;
/* encode the image */
encode(c,frame,pkt,f);
}
/* flush the encoder */
encode(c,NULL,f);
/* add sequence end code to have a real MPEG file */
if (codec->id == AV_CODEC_ID_MPEG1VIDEO || codec->id == AV_CODEC_ID_MPEG2VIDEO)
fwrite(endcode,sizeof(endcode),f);
fclose(f);
avcodec_free_context(&c);
av_frame_free(&frame);
av_packet_free(&pkt);
sleep(10);
return 0;
}
我期望第一次暂停时的RAM内存使用与第二次暂停时的RAM内存使用相同,但相差约55Mo。如果增加编码帧的数量,则这种差异最多为390Mo。我已经在Linux Mint LMDE 4(与Debian 10大致相同)下测试了此代码。
我猜这个内存“泄漏”不是真正的内存泄漏,但是它是libx265使用的一些内部值,可以重新用于其他编码。但是有没有办法通过FFMPEG API释放此内存?
解决方法
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