#include <unistd.h>
static const char *
filter_descr =
"aresample=8000,aformat=sample_fmts=s16:channel_layouts=mono";
static const char *
player =
"ffplay -f s16le -ar 8000 -ac 1 -";
{
}
}
}
}
return 0;
}
{
char args[512];
static const int out_sample_rates[] = { 8000, -1 };
}
"time_base=%d/%d:sample_rate=%d:sample_fmt=%s:channel_layout=0x%"PRIx64,
}
}
}
}
}
args);
}
{
const uint16_t *p = (uint16_t*)
frame->data[0];
const uint16_t *p_end = p + n;
while (p < p_end) {
fputc(*p & 0xff, stdout);
fputc(*p>>8 & 0xff, stdout);
p++;
}
fflush(stdout);
}
int main(
int argc,
char **argv)
{
if (!
frame || !filt_frame) {
perror("Could not allocate frame");
exit(1);
}
if (argc != 2) {
fprintf(stderr,
"Usage: %s file | %s\n", argv[0],
player);
exit(1);
}
while (1) {
break;
break;
}
break;
}
break;
}
while (1) {
break;
}
}
}
}
}
exit(1);
}
exit(0);
}
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
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
uint64_t channel_layout
Audio channel layout.
int sample_rate
samples per second
#define AVERROR_EOF
End of file.
AVFilterContext * buffersink_ctx
#define AV_CH_LAYOUT_MONO
#define av_opt_set_int_list(obj, name, val, term, flags)
Set a binary option to an integer list.
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
static av_cold int end(AVCodecContext *avctx)
void av_get_channel_layout_string(char *buf, int buf_size, int nb_channels, uint64_t channel_layout)
Return a description of a channel layout.
This structure describes decoded (raw) audio or video data.
AVStream ** streams
A list of all streams in the file.
int av_read_frame(AVFormatContext *s, AVPacket *pkt)
Return the next frame of a stream.
A link between two filters.
void avfilter_graph_free(AVFilterGraph **graph)
Free a graph, destroy its links, and set *graph to NULL.
void avformat_close_input(AVFormatContext **s)
Close an opened input AVFormatContext.
int avfilter_graph_create_filter(AVFilterContext **filt_ctx, const AVFilter *filt, const char *name, const char *args, void *opaque, AVFilterGraph *graph_ctx)
Create and add a filter instance into an existing graph.
AVFilterGraph * filter_graph
AVFilterGraph * avfilter_graph_alloc(void)
Allocate a filter graph.
int main(int argc, char **argv)
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
void avfilter_inout_free(AVFilterInOut **inout)
Free the supplied list of AVFilterInOut and set *inout to NULL.
static const char * player
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
const char * filter_descr
static int open_input_file(const char *filename)
AVCodecContext * avcodec_alloc_context3(const AVCodec *codec)
Allocate an AVCodecContext and set its fields to default values.
int attribute_align_arg av_buffersink_get_frame(AVFilterContext *ctx, AVFrame *frame)
Get a frame with filtered data from sink and put it in frame.
int avcodec_receive_frame(AVCodecContext *avctx, AVFrame *frame)
Return decoded output data from a decoder.
static const AVFilterPad outputs[]
static int init_filters(const char *filters_descr)
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.
AVFilterContext * buffersrc_ctx
const AVFilter * avfilter_get_by_name(const char *name)
Get a filter definition matching the given name.
AVCodecParameters * codecpar
Codec parameters associated with this stream.
int avfilter_graph_config(AVFilterGraph *graphctx, void *log_ctx)
Check validity and configure all the links and formats in the graph.
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented.
void avcodec_free_context(AVCodecContext **avctx)
Free the codec context and everything associated with it and write NULL to the provided pointer.
Rational number (pair of numerator and denominator).
AVFilterLink ** inputs
array of pointers to input links
uint64_t channel_layout
channel layout of current buffer (see libavutil/channel_layout.h)
AVFilterInOut * avfilter_inout_alloc(void)
Allocate a single AVFilterInOut entry.
int avcodec_open2(AVCodecContext *avctx, const AVCodec *codec, AVDictionary **options)
Initialize the AVCodecContext to use the given AVCodec.
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 inputs
int av_get_channel_layout_nb_channels(uint64_t channel_layout)
Return the number of channels in the channel layout.
int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options)
Read packets of a media file to get stream information.
#define av_err2str(errnum)
Convenience macro, the return value should be used only directly in function arguments but never stan...
int format
agreed upon media format
enum AVSampleFormat sample_fmt
audio sample format
#define AV_OPT_SEARCH_CHILDREN
Search in possible children of the given object first.
#define AV_LOG_INFO
Standard information.
int channels
number of audio channels
int avcodec_send_packet(AVCodecContext *avctx, const AVPacket *avpkt)
Supply raw packet data as input to a decoder.
int sample_rate
samples per second
int avformat_open_input(AVFormatContext **ps, const char *url, ff_const59 AVInputFormat *fmt, AVDictionary **options)
Open an input stream and read the header.
int avfilter_graph_parse_ptr(AVFilterGraph *graph, const char *filters, AVFilterInOut **inputs, AVFilterInOut **outputs, void *log_ctx)
Add a graph described by a string to a graph.
int avcodec_parameters_to_context(AVCodecContext *codec, const AVCodecParameters *par)
Fill the codec context based on the values from the supplied codec parameters.
int attribute_align_arg av_buffersrc_add_frame_flags(AVFilterContext *ctx, AVFrame *frame, int flags)
Add a frame to the buffer source.
AVSampleFormat
Audio sample formats.
static void print_frame(const AVFrame *frame)
@ AV_BUFFERSRC_FLAG_KEEP_REF
Keep a reference to the frame.
void av_frame_unref(AVFrame *frame)
Unreference all the buffers referenced by frame and reset the frame fields.
@ AV_SAMPLE_FMT_S16
signed 16 bits
static AVFormatContext * fmt_ctx
const char * name
Pad name.
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.
char * av_strdup(const char *s)
Duplicate a string.
int64_t av_get_default_channel_layout(int nb_channels)
Return default channel layout for a given number of channels.
This structure stores compressed data.
A linked-list of the inputs/outputs of the filter chain.
static int audio_stream_index
static void * av_x_if_null(const void *p, const void *x)
Return x default pointer in case p is NULL.
static AVCodecContext * dec_ctx
int av_find_best_stream(AVFormatContext *ic, enum AVMediaType type, int wanted_stream_nb, int related_stream, AVCodec **decoder_ret, int flags)
Find the "best" stream in the file.