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58 int best_samplerate = 0;
65 if (!best_samplerate ||
abs(44100 - *p) <
abs(44100 - best_samplerate))
69 return best_samplerate;
76 int best_nb_channels = 0;
85 if (nb_channels > best_nb_channels) {
87 best_nb_channels = nb_channels;
102 fprintf(stderr,
"Error sending the frame to the encoder\n");
113 fprintf(stderr,
"Error encoding audio frame\n");
122 int main(
int argc,
char **argv)
124 const char *filename;
135 fprintf(stderr,
"Usage: %s <output file>\n", argv[0]);
143 fprintf(stderr,
"Codec not found\n");
149 fprintf(stderr,
"Could not allocate audio codec context\n");
159 fprintf(stderr,
"Encoder does not support sample format %s",
172 fprintf(stderr,
"Could not open codec\n");
176 f = fopen(filename,
"wb");
178 fprintf(stderr,
"Could not open %s\n", filename);
185 fprintf(stderr,
"could not allocate the packet\n");
192 fprintf(stderr,
"Could not allocate audio frame\n");
196 frame->nb_samples =
c->frame_size;
197 frame->format =
c->sample_fmt;
205 fprintf(stderr,
"Could not allocate audio data buffers\n");
211 tincr = 2 *
M_PI * 440.0 /
c->sample_rate;
212 for (
i = 0;
i < 200;
i++) {
220 for (j = 0; j <
c->frame_size; j++) {
221 samples[2*j] = (int)(sin(t) * 10000);
223 for (k = 1; k <
c->ch_layout.nb_channels; k++)
int main(int argc, char **argv)
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
int avcodec_receive_packet(AVCodecContext *avctx, AVPacket *avpkt)
Read encoded data from the encoder.
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
int av_frame_get_buffer(AVFrame *frame, int align)
Allocate new buffer(s) for audio or video data.
#define AV_CHANNEL_LAYOUT_STEREO
#define AVERROR_EOF
End of file.
filter_frame For filters that do not use the this method is called when a frame is pushed to the filter s input It can be called at any time except in a reentrant way If the input frame is enough to produce output
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
const AVCodec * avcodec_find_encoder(enum AVCodecID id)
Find a registered encoder with a matching codec ID.
This structure describes decoded (raw) audio or video data.
int av_frame_make_writable(AVFrame *frame)
Ensure that the frame data is writable, avoiding data copy if possible.
int nb_channels
Number of channels in this layout.
void av_packet_free(AVPacket **pkt)
Free the packet, if the packet is reference counted, it will be unreferenced first.
const attribute_deprecated int * supported_samplerates
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
AVCodecContext * avcodec_alloc_context3(const AVCodec *codec)
Allocate an AVCodecContext and set its fields to default values.
static int check_sample_fmt(const AVCodec *codec, enum AVSampleFormat sample_fmt)
const char * av_get_sample_fmt_name(enum AVSampleFormat sample_fmt)
Return the name of sample_fmt, or NULL if sample_fmt is not recognized.
void avcodec_free_context(AVCodecContext **avctx)
Free the codec context and everything associated with it and write NULL to the provided pointer.
int attribute_align_arg avcodec_open2(AVCodecContext *avctx, const AVCodec *codec, AVDictionary **options)
Initialize the AVCodecContext to use the given AVCodec.
static int select_channel_layout(const AVCodec *codec, AVChannelLayout *dst)
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
const attribute_deprecated AVChannelLayout * ch_layouts
Array of supported channel layouts, terminated with a zeroed layout.
An AVChannelLayout holds information about the channel layout of audio data.
uint8_t ptrdiff_t const uint8_t ptrdiff_t int intptr_t intptr_t int int16_t * dst
static void encode(AVCodecContext *ctx, AVFrame *frame, AVPacket *pkt, FILE *output)
AVPacket * av_packet_alloc(void)
Allocate an AVPacket and set its fields to default values.
#define i(width, name, range_min, range_max)
AVSampleFormat
Audio sample formats.
@ AV_SAMPLE_FMT_S16
signed 16 bits
static int select_sample_rate(const AVCodec *codec)
int avcodec_send_frame(AVCodecContext *avctx, const AVFrame *frame)
Supply a raw video or audio frame to the encoder.
attribute_deprecated enum AVSampleFormat * sample_fmts
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several the filter must be ready for frames arriving randomly on any input any filter with several inputs will most likely require some kind of queuing mechanism It is perfectly acceptable to have a limited queue and to drop frames when the inputs are too unbalanced request_frame For filters that do not use the this method is called when a frame is wanted on an output For a it should directly call filter_frame on the corresponding output For a if there are queued frames already one of these frames should be pushed If the filter should request a frame on one of its repeatedly until at least one frame has been pushed Return or at least make progress towards producing a frame
main external API structure.
Filter the word “frame” indicates either a video frame or a group of audio samples
int av_channel_layout_copy(AVChannelLayout *dst, const AVChannelLayout *src)
Make a copy of a channel layout.
This structure stores compressed data.