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 
init_filter_graph(AVFilterGraph ** graph,AVFilterContext ** src,AVFilterContext ** sink)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. */
process_output(struct AVMD5 * md5,AVFrame * frame)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. */
get_input(AVFrame * frame,int frame_num)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 
main(int argc,char * argv[])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