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Code Issues Releases Activity

doc/examples/transcode_aac: switch to swresample

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Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2013-11-27 11:15:48 +01:00
parent 60b099c371
commit 7497c894cd
2 changed files with 35 additions and 45 deletions
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2
configure vendored
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@ -2277,7 +2277,7 @@ zmq_filter_deps="libzmq"
# examples
muxing_example_deps="avcodec avformat avutil swscale"
transcode_aac_example_deps="avcodec avformat avresample"
transcode_aac_example_deps="avcodec avformat swresample"
# libraries
avcodec_deps="avutil"

78
doc/examples/transcode_aac.c
View File

@ -30,11 +30,12 @@
#include "libavcodec/avcodec.h"
#include "libavutil/audio_fifo.h"
#include "libavutil/avassert.h"
#include "libavutil/avstring.h"
#include "libavutil/frame.h"
#include "libavutil/opt.h"
#include "libavresample/avresample.h"
#include "libswresample/swresample.h"
/** The output bit rate in kbit/s */
#define OUTPUT_BIT_RATE 48000
@ -223,11 +224,11 @@ static int init_input_frame(AVFrame **frame)
/**
* Initialize the audio resampler based on the input and output codec settings.
* If the input and output sample formats differ, a conversion is required
* libavresample takes care of this, but requires initialization.
* libswresample takes care of this, but requires initialization.
*/
static int init_resampler(AVCodecContext *input_codec_context,
AVCodecContext *output_codec_context,
AVAudioResampleContext **resample_context)
SwrContext **resample_context)
{
/**
* Only initialize the resampler if it is necessary, i.e.,
@ -237,35 +238,36 @@ static int init_resampler(AVCodecContext *input_codec_context,
input_codec_context->channels != output_codec_context->channels) {
int error;
/** Create a resampler context for the conversion. */
if (!(*resample_context = avresample_alloc_context())) {
fprintf(stderr, "Could not allocate resample context\n");
return AVERROR(ENOMEM);
}
/**
* Create a resampler context for the conversion.
* Set the conversion parameters.
* Default channel layouts based on the number of channels
* are assumed for simplicity (they are sometimes not detected
* properly by the demuxer and/or decoder).
*/
av_opt_set_int(*resample_context, "in_channel_layout",
av_get_default_channel_layout(input_codec_context->channels), 0);
av_opt_set_int(*resample_context, "out_channel_layout",
av_get_default_channel_layout(output_codec_context->channels), 0);
av_opt_set_int(*resample_context, "in_sample_rate",
input_codec_context->sample_rate, 0);
av_opt_set_int(*resample_context, "out_sample_rate",
output_codec_context->sample_rate, 0);
av_opt_set_int(*resample_context, "in_sample_fmt",
input_codec_context->sample_fmt, 0);
av_opt_set_int(*resample_context, "out_sample_fmt",
output_codec_context->sample_fmt, 0);
*resample_context = swr_alloc_set_opts(NULL,
av_get_default_channel_layout(output_codec_context->channels),
output_codec_context->sample_fmt,
output_codec_context->sample_rate,
av_get_default_channel_layout(input_codec_context->channels),
input_codec_context->sample_fmt,
input_codec_context->sample_rate,
0, NULL);
if (!*resample_context) {
fprintf(stderr, "Could not allocate resample context\n");
return AVERROR(ENOMEM);
}
/**
* Perform a sanity check so that the number of converted samples is
* not greater than the number of samples to be converted.
* If the sample rates differ, this case has to be handled differently
*/
av_assert0(output_codec_context->sample_rate == input_codec_context->sample_rate);
/** Open the resampler with the specified parameters. */
if ((error = avresample_open(*resample_context)) < 0) {
if ((error = swr_init(*resample_context)) < 0) {
fprintf(stderr, "Could not open resample context\n");
avresample_free(resample_context);
swr_free(resample_context);
return error;
}
}
@ -387,30 +389,21 @@ static int init_converted_samples(uint8_t ***converted_input_samples,
* The conversion happens on a per-frame basis, the size of which is specified
* by frame_size.
*/
static int convert_samples(uint8_t **input_data,
static int convert_samples(const uint8_t **input_data,
uint8_t **converted_data, const int frame_size,
AVAudioResampleContext *resample_context)
SwrContext *resample_context)
{
int error;
/** Convert the samples using the resampler. */
if ((error = avresample_convert(resample_context, converted_data, 0,
frame_size, input_data, 0, frame_size)) < 0) {
if ((error = swr_convert(resample_context,
converted_data, frame_size,
input_data , frame_size)) < 0) {
fprintf(stderr, "Could not convert input samples (error '%s')\n",
get_error_text(error));
return error;
}
/**
* Perform a sanity check so that the number of converted samples is
* not greater than the number of samples to be converted.
* If the sample rates differ, this case has to be handled differently
*/
if (avresample_available(resample_context)) {
fprintf(stderr, "Converted samples left over\n");
return AVERROR_EXIT;
}
return 0;
}
@ -447,7 +440,7 @@ static int read_decode_convert_and_store(AVAudioFifo *fifo,
AVFormatContext *input_format_context,
AVCodecContext *input_codec_context,
AVCodecContext *output_codec_context,
AVAudioResampleContext *resampler_context,
SwrContext *resampler_context,
int *finished)
{
/** Temporary storage of the input samples of the frame read from the file. */
@ -484,7 +477,7 @@ static int read_decode_convert_and_store(AVAudioFifo *fifo,
* Convert the input samples to the desired output sample format.
* This requires a temporary storage provided by converted_input_samples.
*/
if (convert_samples(input_frame->extended_data, converted_input_samples,
if (convert_samples((const uint8_t**)input_frame->extended_data, converted_input_samples,
input_frame->nb_samples, resampler_context))
goto cleanup;
@ -646,7 +639,7 @@ int main(int argc, char **argv)
{
AVFormatContext *input_format_context = NULL, *output_format_context = NULL;
AVCodecContext *input_codec_context = NULL, *output_codec_context = NULL;
AVAudioResampleContext *resample_context = NULL;
SwrContext *resample_context = NULL;
AVAudioFifo *fifo = NULL;
int ret = AVERROR_EXIT;
@ -750,10 +743,7 @@ int main(int argc, char **argv)
cleanup:
if (fifo)
av_audio_fifo_free(fifo);
if (resample_context) {
avresample_close(resample_context);
avresample_free(&resample_context);
}
swr_free(&resample_context);
if (output_codec_context)
avcodec_close(output_codec_context);
if (output_format_context) {