我在解码用FFV1编解码器编码的灰色图像时遇到问题。 我成功编码了16位灰度图像(使用 avcodec_receive_packet(...)功能)并将 AvPacket 数据保存到文件中。然后我从文件中读取这些数据并尝试解码(使用 avcodec_decode_video2 或 avcodec_send_packet / avcodec_receive_frame )但没有成功:
我在编码之后和解码之前比较了数据包,并且所有字段和值看起来都是相同的。我甚至尝试在 avcodec_receive_packet (编码函数)之后解码数据包,但是出现相同的错误。
我使用的是ffmpeg的4.0版本,该程序基于 decode_video.c 和 encode_video.c 示例。 当我使用容器(例如avi)来支持从文件读取/写入编码图像时(基于 demuxing_decoding.c 和 muxing.c examples )我成功编码和解码帧用FFV1。但是我不能使用容器,因为我想编码具有不同分辨率的帧并将几个视频源混合在一起。此外,对于数百张图像,压缩级别显着降低(从2.9降至2.2),这也是非常令人惊讶的。
所以我的问题是如何正确保存/读取(从二进制文件而不是容器)并准备AVPacker以使用FFV1进行解码。
非常感谢任何帮助。
解码代码:
extern "C" {
#include <libavcodec/avcodec.h>
#include <libavutil/opt.h>
#include <libavutil/imgutils.h>
}
#pragma warning(disable: 4996)
#define INBUF_SIZE 4096
#define FF_INPUT_BUFFER_PADDING_SIZE 64
uint8_t endcode[4];
AVCodecContext *c, c2;
AVCodec *codec;
int i, ret, x, y;
AVFrame *frame;
AVPacket *pkt, *pkt_temp;
FILE *encodedVideoFile;
AVDictionary *opts = NULL;
uint8_t *video_dst_data[4] = { NULL };
int video_dst_linesize[4];
int imageSize;
uint8_t inbuf[INBUF_SIZE + AV_INPUT_BUFFER_PADDING_SIZE];
/* flush the encoder */
frame = NULL;
encode();
/* add sequence end code to have a real MPEG file */
//fwrite(endcode, 1, sizeof(endcode), encodedVideoFile);
fclose(encodedVideoFile);
avcodec_free_context(&c);
av_frame_free(&frame);
av_packet_free(&pkt);
}
void initDecoding(const char *filename)
{
/* set end of buffer to 0 (this ensures that no overreading happens for damaged MPEG streams) */
memset(inbuf + INBUF_SIZE, 0, AV_INPUT_BUFFER_PADDING_SIZE);
/* find the MPEG-1 video decoder */
codec = avcodec_find_decoder(AV_CODEC_ID_FFV1);
if (!codec) {
fprintf(stderr, "Codec not found\n");
exit(1);
}
c = avcodec_alloc_context3(codec);
if (!c) {
fprintf(stderr, "Could not allocate video codec context\n");
exit(1);
}
/* resolution must be a multiple of two */
c->width = 1280;
c->height = 484;
/* frames per second */
c->time_base.den = 1;
c->time_base.num = 10;
c->bits_per_raw_sample = 16;
c->framerate.den = 10;
c->framerate.num = 1;
c->pix_fmt = AV_PIX_FMT_GRAY16;
//Version of FFV1 codec
c->level = 3;
/* Init the decoders, with or without reference counting */
av_dict_set(&opts, "refcounted_frames", 0 ? "1" : "0", 0);
if ((ret = avcodec_open2(c, codec, &opts)) < 0) {
return;
}
if (avcodec_open2(c, codec, NULL) < 0) {
fprintf(stderr, "Could not open codec\n");
exit(1);
}
ret = av_image_alloc(video_dst_data, video_dst_linesize,
c->width, c->height, c->pix_fmt, 4);
if (ret < 0) {
fprintf(stderr, "Could not allocate raw video buffer\n");
}
encodedVideoFile = fopen(filename, "rb");
if (!encodedVideoFile) {
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, 32);
if (ret < 0) {
fprintf(stderr, "Could not allocate the video frame data\n");
exit(1);
}
/* make sure the frame data is writable */
ret = av_frame_make_writable(frame);
if (ret < 0)
exit(1);
}
void closeDecoding()
{
fclose(encodedVideoFile);
av_parser_close(parser);
avcodec_free_context(&c);
av_frame_free(&frame);
av_packet_free(&pkt);
}
void decodePacket()
{
size_t data_size;
int *got_frame = 0;
read_packt_from_file(pkt, encodedVideoFile);
ret = av_frame_is_writable(frame);
//First decoding function
/*ret = avcodec_decode_video2(c, frame, got_frame, pkt);
if (ret < 0) {
fprintf(stderr, "Error decoding video frame (%s)\n");
}*/
ret = avcodec_send_packet(c, pkt);
if (ret < 0) {
fprintf(stderr, "Error sending a packet for decoding\n");
exit(1);
}
while (ret >= 0) {
ret = avcodec_receive_frame(c, frame);
if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
return;
else if (ret < 0) {
fprintf(stderr, "Error during decoding\n");
exit(1);
}
printf("saving frame %3d\n", c->frame_number);
fflush(stdout);
}
}
size_t read_packt_from_file(AVPacket *packet, FILE *file)
{
size_t ret = 0;
int size;
uint8_t * data;
//av_packet_from_data
ret = fread(packet, sizeof(AVPacket), 1, file);
size = packet->size;
data = new uint8_t[size];
ret = fread(data, size, 1, file);
av_new_packet(packet, size);
av_packet_from_data(packet, data, size);
return ret;
}
//To write encoded AVPacket
size_t write_packt_to_file(AVPacket *packet, FILE *file)
{
size_t ret = 0;
ret = fwrite(packet, sizeof(AVPacket), 1, file);
ret = fwrite(packet->data, packet->size, 1, file);
if (packet->buf) {
fwrite(packet->buf->data, packet->buf->size, 1, file);
}
fflush(file);
return ret;
}