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  1. /*
  2.  * copyright (c) 2013 Andrew Kelley
  3.  *
  4.  * This file is part of FFmpeg.
  5.  *
  6.  * FFmpeg is free software; you can redistribute it and/or
  7.  * modify it under the terms of the GNU Lesser General Public
  8.  * License as published by the Free Software Foundation; either
  9.  * version 2.1 of the License, or (at your option) any later version.
  10.  *
  11.  * FFmpeg is distributed in the hope that it will be useful,
  12.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14.  * Lesser General Public License for more details.
  15.  *
  16.  * You should have received a copy of the GNU Lesser General Public
  17.  * License along with FFmpeg; if not, write to the Free Software
  18.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19.  */
  20.  
  21. /**
  22.  * @file
  23.  * libavfilter API usage example.
  24.  *
  25.  * @example filter_audio.c
  26.  * This example will generate a sine wave audio,
  27.  * pass it through a simple filter chain, and then compute the MD5 checksum of
  28.  * the output data.
  29.  *
  30.  * The filter chain it uses is:
  31.  * (input) -> abuffer -> volume -> aformat -> abuffersink -> (output)
  32.  *
  33.  * abuffer: This provides the endpoint where you can feed the decoded samples.
  34.  * volume: In this example we hardcode it to 0.90.
  35.  * aformat: This converts the samples to the samplefreq, channel layout,
  36.  *          and sample format required by the audio device.
  37.  * abuffersink: This provides the endpoint where you can read the samples after
  38.  *              they have passed through the filter chain.
  39.  */
  40.  
  41. #include <inttypes.h>
  42. #include <math.h>
  43. #include <stdio.h>
  44. #include <stdlib.h>
  45.  
  46. #include "libavutil/channel_layout.h"
  47. #include "libavutil/md5.h"
  48. #include "libavutil/mem.h"
  49. #include "libavutil/opt.h"
  50. #include "libavutil/samplefmt.h"
  51.  
  52. #include "libavfilter/avfilter.h"
  53. #include "libavfilter/buffersink.h"
  54. #include "libavfilter/buffersrc.h"
  55.  
  56. #define INPUT_SAMPLERATE     48000
  57. #define INPUT_FORMAT         AV_SAMPLE_FMT_FLTP
  58. #define INPUT_CHANNEL_LAYOUT AV_CH_LAYOUT_5POINT0
  59.  
  60. #define VOLUME_VAL 0.90
  61.  
  62. static int init_filter_graph(AVFilterGraph **graph, AVFilterContext **src,
  63.                              AVFilterContext **sink)
  64. {
  65.     AVFilterGraph *filter_graph;
  66.     AVFilterContext *abuffer_ctx;
  67.     AVFilter        *abuffer;
  68.     AVFilterContext *volume_ctx;
  69.     AVFilter        *volume;
  70.     AVFilterContext *aformat_ctx;
  71.     AVFilter        *aformat;
  72.     AVFilterContext *abuffersink_ctx;
  73.     AVFilter        *abuffersink;
  74.  
  75.     AVDictionary *options_dict = NULL;
  76.     uint8_t options_str[1024];
  77.     uint8_t ch_layout[64];
  78.  
  79.     int err;
  80.  
  81.     /* Create a new filtergraph, which will contain all the filters. */
  82.     filter_graph = avfilter_graph_alloc();
  83.     if (!filter_graph) {
  84.         fprintf(stderr, "Unable to create filter graph.\n");
  85.         return AVERROR(ENOMEM);
  86.     }
  87.  
  88.     /* Create the abuffer filter;
  89.      * it will be used for feeding the data into the graph. */
  90.     abuffer = avfilter_get_by_name("abuffer");
  91.     if (!abuffer) {
  92.         fprintf(stderr, "Could not find the abuffer filter.\n");
  93.         return AVERROR_FILTER_NOT_FOUND;
  94.     }
  95.  
  96.     abuffer_ctx = avfilter_graph_alloc_filter(filter_graph, abuffer, "src");
  97.     if (!abuffer_ctx) {
  98.         fprintf(stderr, "Could not allocate the abuffer instance.\n");
  99.         return AVERROR(ENOMEM);
  100.     }
  101.  
  102.     /* Set the filter options through the AVOptions API. */
  103.     av_get_channel_layout_string(ch_layout, sizeof(ch_layout), 0, INPUT_CHANNEL_LAYOUT);
  104.     av_opt_set    (abuffer_ctx, "channel_layout", ch_layout,                            AV_OPT_SEARCH_CHILDREN);
  105.     av_opt_set    (abuffer_ctx, "sample_fmt",     av_get_sample_fmt_name(INPUT_FORMAT), AV_OPT_SEARCH_CHILDREN);
  106.     av_opt_set_q  (abuffer_ctx, "time_base",      (AVRational){ 1, INPUT_SAMPLERATE },  AV_OPT_SEARCH_CHILDREN);
  107.     av_opt_set_int(abuffer_ctx, "sample_rate",    INPUT_SAMPLERATE,                     AV_OPT_SEARCH_CHILDREN);
  108.  
  109.     /* Now initialize the filter; we pass NULL options, since we have already
  110.      * set all the options above. */
  111.     err = avfilter_init_str(abuffer_ctx, NULL);
  112.     if (err < 0) {
  113.         fprintf(stderr, "Could not initialize the abuffer filter.\n");
  114.         return err;
  115.     }
  116.  
  117.     /* Create volume filter. */
  118.     volume = avfilter_get_by_name("volume");
  119.     if (!volume) {
  120.         fprintf(stderr, "Could not find the volume filter.\n");
  121.         return AVERROR_FILTER_NOT_FOUND;
  122.     }
  123.  
  124.     volume_ctx = avfilter_graph_alloc_filter(filter_graph, volume, "volume");
  125.     if (!volume_ctx) {
  126.         fprintf(stderr, "Could not allocate the volume instance.\n");
  127.         return AVERROR(ENOMEM);
  128.     }
  129.  
  130.     /* A different way of passing the options is as key/value pairs in a
  131.      * dictionary. */
  132.     av_dict_set(&options_dict, "volume", AV_STRINGIFY(VOLUME_VAL), 0);
  133.     err = avfilter_init_dict(volume_ctx, &options_dict);
  134.     av_dict_free(&options_dict);
  135.     if (err < 0) {
  136.         fprintf(stderr, "Could not initialize the volume filter.\n");
  137.         return err;
  138.     }
  139.  
  140.     /* Create the aformat filter;
  141.      * it ensures that the output is of the format we want. */
  142.     aformat = avfilter_get_by_name("aformat");
  143.     if (!aformat) {
  144.         fprintf(stderr, "Could not find the aformat filter.\n");
  145.         return AVERROR_FILTER_NOT_FOUND;
  146.     }
  147.  
  148.     aformat_ctx = avfilter_graph_alloc_filter(filter_graph, aformat, "aformat");
  149.     if (!aformat_ctx) {
  150.         fprintf(stderr, "Could not allocate the aformat instance.\n");
  151.         return AVERROR(ENOMEM);
  152.     }
  153.  
  154.     /* A third way of passing the options is in a string of the form
  155.      * key1=value1:key2=value2.... */
  156.     snprintf(options_str, sizeof(options_str),
  157.              "sample_fmts=%s:sample_rates=%d:channel_layouts=0x%"PRIx64,
  158.              av_get_sample_fmt_name(AV_SAMPLE_FMT_S16), 44100,
  159.              (uint64_t)AV_CH_LAYOUT_STEREO);
  160.     err = avfilter_init_str(aformat_ctx, options_str);
  161.     if (err < 0) {
  162.         av_log(NULL, AV_LOG_ERROR, "Could not initialize the aformat filter.\n");
  163.         return err;
  164.     }
  165.  
  166.     /* Finally create the abuffersink filter;
  167.      * it will be used to get the filtered data out of the graph. */
  168.     abuffersink = avfilter_get_by_name("abuffersink");
  169.     if (!abuffersink) {
  170.         fprintf(stderr, "Could not find the abuffersink filter.\n");
  171.         return AVERROR_FILTER_NOT_FOUND;
  172.     }
  173.  
  174.     abuffersink_ctx = avfilter_graph_alloc_filter(filter_graph, abuffersink, "sink");
  175.     if (!abuffersink_ctx) {
  176.         fprintf(stderr, "Could not allocate the abuffersink instance.\n");
  177.         return AVERROR(ENOMEM);
  178.     }
  179.  
  180.     /* This filter takes no options. */
  181.     err = avfilter_init_str(abuffersink_ctx, NULL);
  182.     if (err < 0) {
  183.         fprintf(stderr, "Could not initialize the abuffersink instance.\n");
  184.         return err;
  185.     }
  186.  
  187.     /* Connect the filters;
  188.      * in this simple case the filters just form a linear chain. */
  189.     err = avfilter_link(abuffer_ctx, 0, volume_ctx, 0);
  190.     if (err >= 0)
  191.         err = avfilter_link(volume_ctx, 0, aformat_ctx, 0);
  192.     if (err >= 0)
  193.         err = avfilter_link(aformat_ctx, 0, abuffersink_ctx, 0);
  194.     if (err < 0) {
  195.         fprintf(stderr, "Error connecting filters\n");
  196.         return err;
  197.     }
  198.  
  199.     /* Configure the graph. */
  200.     err = avfilter_graph_config(filter_graph, NULL);
  201.     if (err < 0) {
  202.         av_log(NULL, AV_LOG_ERROR, "Error configuring the filter graph\n");
  203.         return err;
  204.     }
  205.  
  206.     *graph = filter_graph;
  207.     *src   = abuffer_ctx;
  208.     *sink  = abuffersink_ctx;
  209.  
  210.     return 0;
  211. }
  212.  
  213. /* Do something useful with the filtered data: this simple
  214.  * example just prints the MD5 checksum of each plane to stdout. */
  215. static int process_output(struct AVMD5 *md5, AVFrame *frame)
  216. {
  217.     int planar     = av_sample_fmt_is_planar(frame->format);
  218.     int channels   = av_get_channel_layout_nb_channels(frame->channel_layout);
  219.     int planes     = planar ? channels : 1;
  220.     int bps        = av_get_bytes_per_sample(frame->format);
  221.     int plane_size = bps * frame->nb_samples * (planar ? 1 : channels);
  222.     int i, j;
  223.  
  224.     for (i = 0; i < planes; i++) {
  225.         uint8_t checksum[16];
  226.  
  227.         av_md5_init(md5);
  228.         av_md5_sum(checksum, frame->extended_data[i], plane_size);
  229.  
  230.         fprintf(stdout, "plane %d: 0x", i);
  231.         for (j = 0; j < sizeof(checksum); j++)
  232.             fprintf(stdout, "%02X", checksum[j]);
  233.         fprintf(stdout, "\n");
  234.     }
  235.     fprintf(stdout, "\n");
  236.  
  237.     return 0;
  238. }
  239.  
  240. /* Construct a frame of audio data to be filtered;
  241.  * this simple example just synthesizes a sine wave. */
  242. static int get_input(AVFrame *frame, int frame_num)
  243. {
  244.     int err, i, j;
  245.  
  246. #define FRAME_SIZE 1024
  247.  
  248.     /* Set up the frame properties and allocate the buffer for the data. */
  249.     frame->sample_rate    = INPUT_SAMPLERATE;
  250.     frame->format         = INPUT_FORMAT;
  251.     frame->channel_layout = INPUT_CHANNEL_LAYOUT;
  252.     frame->nb_samples     = FRAME_SIZE;
  253.     frame->pts            = frame_num * FRAME_SIZE;
  254.  
  255.     err = av_frame_get_buffer(frame, 0);
  256.     if (err < 0)
  257.         return err;
  258.  
  259.     /* Fill the data for each channel. */
  260.     for (i = 0; i < 5; i++) {
  261.         float *data = (float*)frame->extended_data[i];
  262.  
  263.         for (j = 0; j < frame->nb_samples; j++)
  264.             data[j] = sin(2 * M_PI * (frame_num + j) * (i + 1) / FRAME_SIZE);
  265.     }
  266.  
  267.     return 0;
  268. }
  269.  
  270. int main(int argc, char *argv[])
  271. {
  272.     struct AVMD5 *md5;
  273.     AVFilterGraph *graph;
  274.     AVFilterContext *src, *sink;
  275.     AVFrame *frame;
  276.     uint8_t errstr[1024];
  277.     float duration;
  278.     int err, nb_frames, i;
  279.  
  280.     if (argc < 2) {
  281.         fprintf(stderr, "Usage: %s <duration>\n", argv[0]);
  282.         return 1;
  283.     }
  284.  
  285.     duration  = atof(argv[1]);
  286.     nb_frames = duration * INPUT_SAMPLERATE / FRAME_SIZE;
  287.     if (nb_frames <= 0) {
  288.         fprintf(stderr, "Invalid duration: %s\n", argv[1]);
  289.         return 1;
  290.     }
  291.  
  292.     avfilter_register_all();
  293.  
  294.     /* Allocate the frame we will be using to store the data. */
  295.     frame  = av_frame_alloc();
  296.     if (!frame) {
  297.         fprintf(stderr, "Error allocating the frame\n");
  298.         return 1;
  299.     }
  300.  
  301.     md5 = av_md5_alloc();
  302.     if (!md5) {
  303.         fprintf(stderr, "Error allocating the MD5 context\n");
  304.         return 1;
  305.     }
  306.  
  307.     /* Set up the filtergraph. */
  308.     err = init_filter_graph(&graph, &src, &sink);
  309.     if (err < 0) {
  310.         fprintf(stderr, "Unable to init filter graph:");
  311.         goto fail;
  312.     }
  313.  
  314.     /* the main filtering loop */
  315.     for (i = 0; i < nb_frames; i++) {
  316.         /* get an input frame to be filtered */
  317.         err = get_input(frame, i);
  318.         if (err < 0) {
  319.             fprintf(stderr, "Error generating input frame:");
  320.             goto fail;
  321.         }
  322.  
  323.         /* Send the frame to the input of the filtergraph. */
  324.         err = av_buffersrc_add_frame(src, frame);
  325.         if (err < 0) {
  326.             av_frame_unref(frame);
  327.             fprintf(stderr, "Error submitting the frame to the filtergraph:");
  328.             goto fail;
  329.         }
  330.  
  331.         /* Get all the filtered output that is available. */
  332.         while ((err = av_buffersink_get_frame(sink, frame)) >= 0) {
  333.             /* now do something with our filtered frame */
  334.             err = process_output(md5, frame);
  335.             if (err < 0) {
  336.                 fprintf(stderr, "Error processing the filtered frame:");
  337.                 goto fail;
  338.             }
  339.             av_frame_unref(frame);
  340.         }
  341.  
  342.         if (err == AVERROR(EAGAIN)) {
  343.             /* Need to feed more frames in. */
  344.             continue;
  345.         } else if (err == AVERROR_EOF) {
  346.             /* Nothing more to do, finish. */
  347.             break;
  348.         } else if (err < 0) {
  349.             /* An error occurred. */
  350.             fprintf(stderr, "Error filtering the data:");
  351.             goto fail;
  352.         }
  353.     }
  354.  
  355.     avfilter_graph_free(&graph);
  356.     av_frame_free(&frame);
  357.     av_freep(&md5);
  358.  
  359.     return 0;
  360.  
  361. fail:
  362.     av_strerror(err, errstr, sizeof(errstr));
  363.     fprintf(stderr, "%s\n", errstr);
  364.     return 1;
  365. }
  366.