2 * copyright (c) 2013 Andrew Kelley
4 * This file is part of FFmpeg.
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.
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.
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
23 * libavfilter API usage example.
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
30 * The filter chain it uses is:
31 * (input) -> abuffer -> volume -> aformat -> abuffersink -> (output)
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.
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"
52 #include "libavfilter/avfilter.h"
53 #include "libavfilter/buffersink.h"
54 #include "libavfilter/buffersrc.h"
56 #define INPUT_SAMPLERATE 48000
57 #define INPUT_FORMAT AV_SAMPLE_FMT_FLTP
58 #define INPUT_CHANNEL_LAYOUT AV_CH_LAYOUT_5POINT0
60 #define VOLUME_VAL 0.90
62 static int init_filter_graph(AVFilterGraph
**graph
, AVFilterContext
**src
,
63 AVFilterContext
**sink
)
65 AVFilterGraph
*filter_graph
;
66 AVFilterContext
*abuffer_ctx
;
68 AVFilterContext
*volume_ctx
;
70 AVFilterContext
*aformat_ctx
;
72 AVFilterContext
*abuffersink_ctx
;
73 AVFilter
*abuffersink
;
75 AVDictionary
*options_dict
= NULL
;
76 uint8_t options_str
[1024];
77 uint8_t ch_layout
[64];
81 /* Create a new filtergraph, which will contain all the filters. */
82 filter_graph
= avfilter_graph_alloc();
84 fprintf(stderr
, "Unable to create filter graph.\n");
85 return AVERROR(ENOMEM
);
88 /* Create the abuffer filter;
89 * it will be used for feeding the data into the graph. */
90 abuffer
= avfilter_get_by_name("abuffer");
92 fprintf(stderr
, "Could not find the abuffer filter.\n");
93 return AVERROR_FILTER_NOT_FOUND
;
96 abuffer_ctx
= avfilter_graph_alloc_filter(filter_graph
, abuffer
, "src");
98 fprintf(stderr
, "Could not allocate the abuffer instance.\n");
99 return AVERROR(ENOMEM
);
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
);
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
);
113 fprintf(stderr
, "Could not initialize the abuffer filter.\n");
117 /* Create volume filter. */
118 volume
= avfilter_get_by_name("volume");
120 fprintf(stderr
, "Could not find the volume filter.\n");
121 return AVERROR_FILTER_NOT_FOUND
;
124 volume_ctx
= avfilter_graph_alloc_filter(filter_graph
, volume
, "volume");
126 fprintf(stderr
, "Could not allocate the volume instance.\n");
127 return AVERROR(ENOMEM
);
130 /* A different way of passing the options is as key/value pairs in a
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
);
136 fprintf(stderr
, "Could not initialize the volume filter.\n");
140 /* Create the aformat filter;
141 * it ensures that the output is of the format we want. */
142 aformat
= avfilter_get_by_name("aformat");
144 fprintf(stderr
, "Could not find the aformat filter.\n");
145 return AVERROR_FILTER_NOT_FOUND
;
148 aformat_ctx
= avfilter_graph_alloc_filter(filter_graph
, aformat
, "aformat");
150 fprintf(stderr
, "Could not allocate the aformat instance.\n");
151 return AVERROR(ENOMEM
);
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
);
162 av_log(NULL
, AV_LOG_ERROR
, "Could not initialize the aformat filter.\n");
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");
170 fprintf(stderr
, "Could not find the abuffersink filter.\n");
171 return AVERROR_FILTER_NOT_FOUND
;
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
);
180 /* This filter takes no options. */
181 err
= avfilter_init_str(abuffersink_ctx
, NULL
);
183 fprintf(stderr
, "Could not initialize the abuffersink instance.\n");
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);
191 err
= avfilter_link(volume_ctx
, 0, aformat_ctx
, 0);
193 err
= avfilter_link(aformat_ctx
, 0, abuffersink_ctx
, 0);
195 fprintf(stderr
, "Error connecting filters\n");
199 /* Configure the graph. */
200 err
= avfilter_graph_config(filter_graph
, NULL
);
202 av_log(NULL
, AV_LOG_ERROR
, "Error configuring the filter graph\n");
206 *graph
= filter_graph
;
208 *sink
= abuffersink_ctx
;
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
)
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
);
224 for (i
= 0; i
< planes
; i
++) {
225 uint8_t checksum
[16];
228 av_md5_sum(checksum
, frame
->extended_data
[i
], plane_size
);
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");
235 fprintf(stdout
, "\n");
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
)
246 #define FRAME_SIZE 1024
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
;
255 err
= av_frame_get_buffer(frame
, 0);
259 /* Fill the data for each channel. */
260 for (i
= 0; i
< 5; i
++) {
261 float *data
= (float*)frame
->extended_data
[i
];
263 for (j
= 0; j
< frame
->nb_samples
; j
++)
264 data
[j
] = sin(2 * M_PI
* (frame_num
+ j
) * (i
+ 1) / FRAME_SIZE
);
270 int main(int argc
, char *argv
[])
273 AVFilterGraph
*graph
;
274 AVFilterContext
*src
, *sink
;
276 uint8_t errstr
[1024];
278 int err
, nb_frames
, i
;
281 fprintf(stderr
, "Usage: %s <duration>\n", argv
[0]);
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]);
292 avfilter_register_all();
294 /* Allocate the frame we will be using to store the data. */
295 frame
= av_frame_alloc();
297 fprintf(stderr
, "Error allocating the frame\n");
301 md5
= av_md5_alloc();
303 fprintf(stderr
, "Error allocating the MD5 context\n");
307 /* Set up the filtergraph. */
308 err
= init_filter_graph(&graph
, &src
, &sink
);
310 fprintf(stderr
, "Unable to init filter graph:");
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
);
319 fprintf(stderr
, "Error generating input frame:");
323 /* Send the frame to the input of the filtergraph. */
324 err
= av_buffersrc_add_frame(src
, frame
);
326 av_frame_unref(frame
);
327 fprintf(stderr
, "Error submitting the frame to the filtergraph:");
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
);
336 fprintf(stderr
, "Error processing the filtered frame:");
339 av_frame_unref(frame
);
342 if (err
== AVERROR(EAGAIN
)) {
343 /* Need to feed more frames in. */
345 } else if (err
== AVERROR_EOF
) {
346 /* Nothing more to do, finish. */
348 } else if (err
< 0) {
349 /* An error occurred. */
350 fprintf(stderr
, "Error filtering the data:");
355 avfilter_graph_free(&graph
);
356 av_frame_free(&frame
);
362 av_strerror(err
, errstr
, sizeof(errstr
));
363 fprintf(stderr
, "%s\n", errstr
);