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Autres articles (42)
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Keeping control of your media in your hands
13 avril 2011, parThe vocabulary used on this site and around MediaSPIP in general, aims to avoid reference to Web 2.0 and the companies that profit from media-sharing.
While using MediaSPIP, you are invited to avoid using words like "Brand", "Cloud" and "Market".
MediaSPIP is designed to facilitate the sharing of creative media online, while allowing authors to retain complete control of their work.
MediaSPIP aims to be accessible to as many people as possible and development is based on expanding the (...) -
Publier sur MédiaSpip
13 juin 2013Puis-je poster des contenus à partir d’une tablette Ipad ?
Oui, si votre Médiaspip installé est à la version 0.2 ou supérieure. Contacter au besoin l’administrateur de votre MédiaSpip pour le savoir -
Soumettre améliorations et plugins supplémentaires
10 avril 2011Si vous avez développé une nouvelle extension permettant d’ajouter une ou plusieurs fonctionnalités utiles à MediaSPIP, faites le nous savoir et son intégration dans la distribution officielle sera envisagée.
Vous pouvez utiliser la liste de discussion de développement afin de le faire savoir ou demander de l’aide quant à la réalisation de ce plugin. MediaSPIP étant basé sur SPIP, il est également possible d’utiliser le liste de discussion SPIP-zone de SPIP pour (...)
Sur d’autres sites (8745)
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aarch64 : hevc : Reorder epel_hv functions to prepare for templating
25 mars 2024, par Martin Storsjö -
How to play audio using libao and FFmpeg in C ?
12 mars 2024, par OmegaLol21I am trying to create a simple prototype application that opens a video file and plays its audio. I am using the FFmpeg libraries (libavcodec, libavformat, etc) to open and decode the video, and I am attempting to use libao to play the audio. I tried looking up code examples but a lot of them either don't work or use deprecated functions.


So far, I managed to come up with this :


#include <libavcodec></libavcodec>avcodec.h>
#include <libavformat></libavformat>avformat.h>
#include <libswresample></libswresample>swresample.h>
#include <ao></ao>ao.h>

int main(int argc, char** argv) {
 AVFormatContext* format_ctx = avformat_alloc_context();
 int audio_stream_index = -1;
 AVCodecContext* codec_ctx = NULL;
 AVCodec* codec = NULL;
 AVPacket packet;
 AVFrame* frame = NULL;
 ao_device* device = NULL;
 ao_sample_format sample_format;
 uint8_t* output_buffer = NULL;
 int output_linesize;

 avformat_open_input(&format_ctx, "test.mp4", NULL, NULL);
 avformat_find_stream_info(format_ctx, NULL);

 for (int i = 0; i < format_ctx->nb_streams; i++) {
 if (format_ctx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
 audio_stream_index = i;
 break;
 }
 }

 codec_ctx = avcodec_alloc_context3(NULL);
 avcodec_parameters_to_context(codec_ctx, format_ctx->streams[audio_stream_index]->codecpar);
 codec = avcodec_find_decoder(codec_ctx->codec_id);
 avcodec_open2(codec_ctx, codec, NULL);

 // Initialize libao
 ao_initialize();
 int driver_id = ao_default_driver_id();

 sample_format.bits = 16;
 sample_format.channels = 2;
 sample_format.rate = 44100;
 sample_format.byte_format = AO_FMT_NATIVE;
 sample_format.matrix = 0;
 device = ao_open_live(driver_id, &sample_format, NULL);
 if (!device) {
 fprintf(stderr, "Could not open audio device\n");
 return 1;
 }

 frame = av_frame_alloc();

 while (av_read_frame(format_ctx, &packet) >= 0) {
 if (packet.stream_index == audio_stream_index) {
 int ret = avcodec_send_packet(codec_ctx, &packet);
 if (ret < 0) {
 fprintf(stderr, "Error sending packet for decoding\n");
 break;
 }

 while (ret >= 0) {
 ret = avcodec_receive_frame(codec_ctx, frame);
 if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
 break;
 }
 else if (ret < 0) {
 fprintf(stderr, "Error during decoding\n");
 break;
 }

 ao_play(device, (char*)frame->data[0], frame->nb_samples * 2 * frame->channels);
 }
 }
 av_packet_unref(&packet);
 }

 // Clean up
 av_frame_free(&frame);
 avcodec_free_context(&codec_ctx);
 avformat_close_input(&format_ctx);
 ao_close(device);
 ao_shutdown();
 av_freep(&output_buffer);

 return 0;
}


This is the closest I have gotten to play audio. It plays audio but there is a lot of static sound in the background. I did try using using
frame->linesize[0]fornum_bytesinao_playbut that didn't produce a sound that sounded at all like the video.

Is there something I am doing wrong or missing ?


EDIT : While doing more testing, I managed to find out that the above code sample outputs pure static in the left speaker, however, in the right speaker, it does play the audio, albeit heavily distorted ?


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aarch64 : hevc : Split the qpel_*_hv functions into two parts
21 mars 2024, par Martin Storsjö
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