125 lines
3.3 KiB
C
125 lines
3.3 KiB
C
#include <libavformat/avformat.h>
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#include <libavcodec/avcodec.h>
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#include <stdio.h>
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#include "png.h"
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#include "util.h"
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int main(int argc, char *argv[])
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{
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AVFormatContext *format = NULL;
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AVCodecContext *vctx = NULL;
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AVStream *vstream = NULL;
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AVCodec *vcodec = NULL;
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AVFrame *frame = NULL;
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AVPacket pkt;
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int found = 0;
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if (argc != 4) {
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printf("Expected an input, a time, and an output\n");
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return -1;
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}
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av_log_set_level(AV_LOG_QUIET);
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const char *input = argv[1];
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const char *output = argv[3];
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AVRational time = av_d2q(atof(argv[2]), INT_MAX);
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if (open_input_correct_demuxer(&format, input) != 0) {
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printf("Couldn't read file\n");
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return -1;
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}
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if (avformat_find_stream_info(format, NULL) < 0) {
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printf("Couldn't read file \n");
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return -1;
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}
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int vstream_idx = av_find_best_stream(format, AVMEDIA_TYPE_VIDEO, -1, -1, &vcodec, 0);
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if (vstream_idx < 0) {
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printf("Couldn't read file\n");
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return -1;
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}
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vstream = format->streams[vstream_idx];
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// Set up decoding context
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vctx = avcodec_alloc_context3(vcodec);
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if (!vctx) {
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printf("Couldn't read file\n");
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return -1;
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}
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if (avcodec_parameters_to_context(vctx, vstream->codecpar) < 0) {
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printf("Couldn't read file\n");
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return -1;
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}
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if (avcodec_open2(vctx, vcodec, NULL) < 0) {
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printf("Couldn't read file\n");
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return -1;
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}
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frame = av_frame_alloc();
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if (!frame) {
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printf("Couldn't read file\n");
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return -1;
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}
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// Loop until we get to the first video frame past the intended pts,
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// decoding all video frames along the way.
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while (!found && av_read_frame(format, &pkt) >= 0) {
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if (pkt.stream_index == vstream_idx) {
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AVRational cur_time = { pkt.pts, vstream->time_base.den };
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AVRational next_time = { pkt.pts + pkt.duration, vstream->time_base.den };
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if (avcodec_send_packet(vctx, &pkt) != 0) {
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// Decoder returned an error
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printf("Couldn't read file\n");
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return -1;
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}
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int ret = avcodec_receive_frame(vctx, frame);
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if (ret == AVERROR(EAGAIN)) {
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// Need more data, can't receive frame yet
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continue;
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}
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if (ret != 0) {
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// Decoder returned an error
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printf("Couldn't read file\n");
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return -1;
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}
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// If this is the first frame past the requested time or the
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// current frame contains the requested time, pick this frame.
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if (av_cmp_q(cur_time, time) >= 0 || (av_cmp_q(cur_time, time) <= 0 && av_cmp_q(next_time, time) >= 0)) {
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found = 1;
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// Found the frame; write to the provided file
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if (mediatools_write_frame_to_png(frame, output) < 0) {
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printf("Couldn't read file\n");
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return -1;
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}
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}
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}
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av_packet_unref(&pkt);
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}
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if (!found) {
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printf("Couldn't read file\n");
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return -1;
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}
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av_frame_free(&frame);
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avcodec_free_context(&vctx);
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avformat_close_input(&format);
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return 0;
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}
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