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  1. /*
  2.  * Copyright (c) 2010 Nicolas George
  3.  * Copyright (c) 2011 Stefano Sabatini
  4.  *
  5.  * Permission is hereby granted, free of charge, to any person obtaining a copy
  6.  * of this software and associated documentation files (the "Software"), to deal
  7.  * in the Software without restriction, including without limitation the rights
  8.  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  9.  * copies of the Software, and to permit persons to whom the Software is
  10.  * furnished to do so, subject to the following conditions:
  11.  *
  12.  * The above copyright notice and this permission notice shall be included in
  13.  * all copies or substantial portions of the Software.
  14.  *
  15.  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16.  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17.  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  18.  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19.  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  20.  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  21.  * THE SOFTWARE.
  22.  */
  23.  
  24. /**
  25.  * @file
  26.  * API example for decoding and filtering
  27.  * @example filtering_video.c
  28.  */
  29.  
  30. #define _XOPEN_SOURCE 600 /* for usleep */
  31. #include <unistd.h>
  32.  
  33. #include <libavcodec/avcodec.h>
  34. #include <libavformat/avformat.h>
  35. #include <libavfilter/avfiltergraph.h>
  36. #include <libavfilter/avcodec.h>
  37. #include <libavfilter/buffersink.h>
  38. #include <libavfilter/buffersrc.h>
  39. #include <libavutil/opt.h>
  40.  
  41. const char *filter_descr = "scale=78:24,transpose=cclock";
  42. /* other way:
  43.    scale=78:24 [scl]; [scl] transpose=cclock // assumes "[in]" and "[out]" to be input output pads respectively
  44.  */
  45.  
  46. static AVFormatContext *fmt_ctx;
  47. static AVCodecContext *dec_ctx;
  48. AVFilterContext *buffersink_ctx;
  49. AVFilterContext *buffersrc_ctx;
  50. AVFilterGraph *filter_graph;
  51. static int video_stream_index = -1;
  52. static int64_t last_pts = AV_NOPTS_VALUE;
  53.  
  54. static int open_input_file(const char *filename)
  55. {
  56.     int ret;
  57.     AVCodec *dec;
  58.  
  59.     if ((ret = avformat_open_input(&fmt_ctx, filename, NULL, NULL)) < 0) {
  60.         av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");
  61.         return ret;
  62.     }
  63.  
  64.     if ((ret = avformat_find_stream_info(fmt_ctx, NULL)) < 0) {
  65.         av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");
  66.         return ret;
  67.     }
  68.  
  69.     /* select the video stream */
  70.     ret = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, &dec, 0);
  71.     if (ret < 0) {
  72.         av_log(NULL, AV_LOG_ERROR, "Cannot find a video stream in the input file\n");
  73.         return ret;
  74.     }
  75.     video_stream_index = ret;
  76.     dec_ctx = fmt_ctx->streams[video_stream_index]->codec;
  77.     av_opt_set_int(dec_ctx, "refcounted_frames", 1, 0);
  78.  
  79.     /* init the video decoder */
  80.     if ((ret = avcodec_open2(dec_ctx, dec, NULL)) < 0) {
  81.         av_log(NULL, AV_LOG_ERROR, "Cannot open video decoder\n");
  82.         return ret;
  83.     }
  84.  
  85.     return 0;
  86. }
  87.  
  88. static int init_filters(const char *filters_descr)
  89. {
  90.     char args[512];
  91.     int ret = 0;
  92.     AVFilter *buffersrc  = avfilter_get_by_name("buffer");
  93.     AVFilter *buffersink = avfilter_get_by_name("buffersink");
  94.     AVFilterInOut *outputs = avfilter_inout_alloc();
  95.     AVFilterInOut *inputs  = avfilter_inout_alloc();
  96.     AVRational time_base = fmt_ctx->streams[video_stream_index]->time_base;
  97.     enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE };
  98.  
  99.     filter_graph = avfilter_graph_alloc();
  100.     if (!outputs || !inputs || !filter_graph) {
  101.         ret = AVERROR(ENOMEM);
  102.         goto end;
  103.     }
  104.  
  105.     /* buffer video source: the decoded frames from the decoder will be inserted here. */
  106.     snprintf(args, sizeof(args),
  107.             "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
  108.             dec_ctx->width, dec_ctx->height, dec_ctx->pix_fmt,
  109.             time_base.num, time_base.den,
  110.             dec_ctx->sample_aspect_ratio.num, dec_ctx->sample_aspect_ratio.den);
  111.  
  112.     ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in",
  113.                                        args, NULL, filter_graph);
  114.     if (ret < 0) {
  115.         av_log(NULL, AV_LOG_ERROR, "Cannot create buffer source\n");
  116.         goto end;
  117.     }
  118.  
  119.     /* buffer video sink: to terminate the filter chain. */
  120.     ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out",
  121.                                        NULL, NULL, filter_graph);
  122.     if (ret < 0) {
  123.         av_log(NULL, AV_LOG_ERROR, "Cannot create buffer sink\n");
  124.         goto end;
  125.     }
  126.  
  127.     ret = av_opt_set_int_list(buffersink_ctx, "pix_fmts", pix_fmts,
  128.                               AV_PIX_FMT_NONE, AV_OPT_SEARCH_CHILDREN);
  129.     if (ret < 0) {
  130.         av_log(NULL, AV_LOG_ERROR, "Cannot set output pixel format\n");
  131.         goto end;
  132.     }
  133.  
  134.     /*
  135.      * Set the endpoints for the filter graph. The filter_graph will
  136.      * be linked to the graph described by filters_descr.
  137.      */
  138.  
  139.     /*
  140.      * The buffer source output must be connected to the input pad of
  141.      * the first filter described by filters_descr; since the first
  142.      * filter input label is not specified, it is set to "in" by
  143.      * default.
  144.      */
  145.     outputs->name       = av_strdup("in");
  146.     outputs->filter_ctx = buffersrc_ctx;
  147.     outputs->pad_idx    = 0;
  148.     outputs->next       = NULL;
  149.  
  150.     /*
  151.      * The buffer sink input must be connected to the output pad of
  152.      * the last filter described by filters_descr; since the last
  153.      * filter output label is not specified, it is set to "out" by
  154.      * default.
  155.      */
  156.     inputs->name       = av_strdup("out");
  157.     inputs->filter_ctx = buffersink_ctx;
  158.     inputs->pad_idx    = 0;
  159.     inputs->next       = NULL;
  160.  
  161.     if ((ret = avfilter_graph_parse_ptr(filter_graph, filters_descr,
  162.                                     &inputs, &outputs, NULL)) < 0)
  163.         goto end;
  164.  
  165.     if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)
  166.         goto end;
  167.  
  168. end:
  169.     avfilter_inout_free(&inputs);
  170.     avfilter_inout_free(&outputs);
  171.  
  172.     return ret;
  173. }
  174.  
  175. static void display_frame(const AVFrame *frame, AVRational time_base)
  176. {
  177.     int x, y;
  178.     uint8_t *p0, *p;
  179.     int64_t delay;
  180.  
  181.     if (frame->pts != AV_NOPTS_VALUE) {
  182.         if (last_pts != AV_NOPTS_VALUE) {
  183.             /* sleep roughly the right amount of time;
  184.              * usleep is in microseconds, just like AV_TIME_BASE. */
  185.             delay = av_rescale_q(frame->pts - last_pts,
  186.                                  time_base, AV_TIME_BASE_Q);
  187.             if (delay > 0 && delay < 1000000)
  188.                 usleep(delay);
  189.         }
  190.         last_pts = frame->pts;
  191.     }
  192.  
  193.     /* Trivial ASCII grayscale display. */
  194.     p0 = frame->data[0];
  195.     puts("\033c");
  196.     for (y = 0; y < frame->height; y++) {
  197.         p = p0;
  198.         for (x = 0; x < frame->width; x++)
  199.             putchar(" .-+#"[*(p++) / 52]);
  200.         putchar('\n');
  201.         p0 += frame->linesize[0];
  202.     }
  203.     fflush(stdout);
  204. }
  205.  
  206. int main(int argc, char **argv)
  207. {
  208.     int ret;
  209.     AVPacket packet;
  210.     AVFrame *frame = av_frame_alloc();
  211.     AVFrame *filt_frame = av_frame_alloc();
  212.     int got_frame;
  213.  
  214.     if (!frame || !filt_frame) {
  215.         perror("Could not allocate frame");
  216.         exit(1);
  217.     }
  218.     if (argc != 2) {
  219.         fprintf(stderr, "Usage: %s file\n", argv[0]);
  220.         exit(1);
  221.     }
  222.  
  223.     av_register_all();
  224.     avfilter_register_all();
  225.  
  226.     if ((ret = open_input_file(argv[1])) < 0)
  227.         goto end;
  228.     if ((ret = init_filters(filter_descr)) < 0)
  229.         goto end;
  230.  
  231.     /* read all packets */
  232.     while (1) {
  233.         if ((ret = av_read_frame(fmt_ctx, &packet)) < 0)
  234.             break;
  235.  
  236.         if (packet.stream_index == video_stream_index) {
  237.             got_frame = 0;
  238.             ret = avcodec_decode_video2(dec_ctx, frame, &got_frame, &packet);
  239.             if (ret < 0) {
  240.                 av_log(NULL, AV_LOG_ERROR, "Error decoding video\n");
  241.                 break;
  242.             }
  243.  
  244.             if (got_frame) {
  245.                 frame->pts = av_frame_get_best_effort_timestamp(frame);
  246.  
  247.                 /* push the decoded frame into the filtergraph */
  248.                 if (av_buffersrc_add_frame_flags(buffersrc_ctx, frame, AV_BUFFERSRC_FLAG_KEEP_REF) < 0) {
  249.                     av_log(NULL, AV_LOG_ERROR, "Error while feeding the filtergraph\n");
  250.                     break;
  251.                 }
  252.  
  253.                 /* pull filtered frames from the filtergraph */
  254.                 while (1) {
  255.                     ret = av_buffersink_get_frame(buffersink_ctx, filt_frame);
  256.                     if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
  257.                         break;
  258.                     if (ret < 0)
  259.                         goto end;
  260.                     display_frame(filt_frame, buffersink_ctx->inputs[0]->time_base);
  261.                     av_frame_unref(filt_frame);
  262.                 }
  263.                 av_frame_unref(frame);
  264.             }
  265.         }
  266.         av_free_packet(&packet);
  267.     }
  268. end:
  269.     avfilter_graph_free(&filter_graph);
  270.     avcodec_close(dec_ctx);
  271.     avformat_close_input(&fmt_ctx);
  272.     av_frame_free(&frame);
  273.     av_frame_free(&filt_frame);
  274.  
  275.     if (ret < 0 && ret != AVERROR_EOF) {
  276.         fprintf(stderr, "Error occurred: %s\n", av_err2str(ret));
  277.         exit(1);
  278.     }
  279.  
  280.     exit(0);
  281. }
  282.