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Mot : - Tags -/copyleft

Autres articles (112)

Personnaliser en ajoutant son logo, sa bannière ou son image de fond

5 septembre 2013, par kent1

Certains thèmes prennent en compte trois éléments de personnalisation : l’ajout d’un logo ; l’ajout d’une bannière l’ajout d’une image de fond ;
Websites made with MediaSPIP

2 mai 2011, par kent1

This page lists some websites based on MediaSPIP.
Creating farms of unique websites

13 avril 2011, par kent1

MediaSPIP platforms can be installed as a farm, with a single "core" hosted on a dedicated server and used by multiple websites.
This allows (among other things) : implementation costs to be shared between several different projects / individuals rapid deployment of multiple unique sites creation of groups of like-minded sites, making it possible to browse media in a more controlled and selective environment than the major "open" (...)

1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | ... | 38

Sur d’autres sites (10509)

lavu/tx : implement aarch64 NEON SIMD FFT

3 février 2022, par Lynne

lavu/tx : implement aarch64 NEON SIMD FFT
The fastest fast Fourier transform in not just the west, but the world,

now for the most popular toy ISA.
On a high level, it follows the design of the AVX2 version closely,

with the exception that the input is slightly less permuted as we don't have

to do lane switching with the input on double 4pt and 8pt.
On a low level, the lack of subadd/addsub instructions REALLY penalizes

any attempt at writing an FFT. That single register matters a lot,

and reloading it simply takes unacceptably long.

In x86 land, vendors would've noticed developers need this.

In ARM land, you get a badly designed complex multiplication instruction

we cannot use, that's not present on 95% of devices. Because only

compilers matter, right ?
Future optimization options are very few, perhaps better register

management to use more ld1/st1s.
All timings below are in cycles :

A53 :

Length | C           | New (lavu)  | Old (lavc)  | FFTW

 |-------------|-------------|-------------|-----

4      |         842 | 420         | 1210        | 1460

8      |        1538 | 1020        | 1850        | 2520

16     |        3717 | 1900        | 3700        | 3990

32     |        9156 | 4070        | 8289        | 8860

64     |       21160 | 9931        | 18600       | 19625

128    |       49180 | 23278       | 41922       | 41922

256    |      112073 | 53876       | 93202       | 101092

512    |      252864 | 122884      | 205897      | 207868

1024   |      560512 | 278322      | 458071      | 453053

2048   |     1295402 | 775835      | 1038205     | 1020265

4096   |     3281263 | 2021221     | 2409718     | 2577554

8192   |     8577845 | 4780526     | 5673041     | 6802722
Apple M1

New  - Total for len 512 reps 2097152 = 1.459141 s

Old  - Total for len 512 reps 2097152 = 2.251344 s

FFTW - Total for len 512 reps 2097152 = 1.868429 s
New  - Total for len 1024 reps 4194304 = 6.490080 s

Old  - Total for len 1024 reps 4194304 = 9.604949 s

FFTW - Total for len 1024 reps 4194304 = 7.889281 s
New  - Total for len 16384 reps 262144 = 10.374001 s

Old  - Total for len 16384 reps 262144 = 15.266713 s

FFTW - Total for len 16384 reps 262144 = 12.341745 s
New  - Total for len 65536 reps 8192 = 1.769812 s

Old  - Total for len 65536 reps 8192 = 4.209413 s

FFTW - Total for len 65536 reps 8192 = 3.012365 s
New  - Total for len 131072 reps 4096 = 1.942836 s

Old  - Segfaults

FFTW - Total for len 131072 reps 4096 = 3.713713 s
Thanks to wbs for some simplifications, assembler fixes and a review

and to jannau for giving it a look.

[D H] libavutil/aarch64/Makefile
[D H] libavutil/aarch64/tx_float_init.c
[D H] libavutil/aarch64/tx_float_neon.S
[D H] libavutil/tx.c
[D H] libavutil/tx_priv.h

SDL Audio - Plays only Static Noise

19 août 2019, par bcpermafrost

Im having an issue with playing audio.

Im new to the SDL World of things so im learning from a tutorial.

http://dranger.com/ffmpeg/tutorial03.html

As far as audio goes, i have exactly what he put down and didnt get the result he says I should get. In the end of the lesson he specifies that the audio should play normally. However all i get is excessively loud static noise. This leads me to believe that the packets arent being read correctly. However I have no idea how to debug or look for the issue.

Here is my main loop for parsing the packets :

 while (av_read_frame(pFormatCtx, &amp;packet) >= 0) {



         if (packet.stream_index == videoStream) {

             avcodec_decode_video2(pCodecCtx, pFrame, &amp;frameFinished, &amp;packet);



             if (frameFinished){



                 AVPicture pict;



                 pict.data[0] = yPlane;

                 pict.data[1] = uPlane;

                 pict.data[2] = vPlane;

                 pict.linesize[0] = pCodecCtx->width;

                 pict.linesize[1] = uvPitch;

                 pict.linesize[2] = uvPitch;



                 sws_scale(sws_ctx,

                     pFrame->data, pFrame->linesize,

                     0, pCodecCtx->height,

                     pict.data, pict.linesize);



                 //SDL_UnlockTexture(bmp);



                 SDL_UpdateYUVTexture(bmp, 0, 

                     yPlane, pCodecCtx->width, 

                     uPlane, uvPitch, 

                     vPlane, uvPitch);





                 SDL_RenderClear(renderer);

                 SDL_RenderCopy(renderer, bmp, NULL, NULL);

                 SDL_RenderPresent(renderer);





                 av_free_packet(&amp;packet);





             }



         }

         else if (packet.stream_index == audioStream) { 

             packet_queue_put(&amp;audioq, &amp;packet);



         }

         else

             av_free_packet(&amp;packet);







         SDL_PollEvent(&amp;event);



         switch (event.type) {

         case SDL_QUIT:

             quit = 1;

             SDL_DestroyTexture(bmp);

             SDL_DestroyRenderer(renderer);

             SDL_DestroyWindow(screen);

             SDL_Quit();

             exit(0);

             break;

         default:

             break;



         }



     }

this is my initialization of the audio device :

aCodecCtxOrig = pFormatCtx->streams[audioStream]->codec;

    aCodec = avcodec_find_decoder(aCodecCtxOrig->codec_id);

    if (!aCodec) {

        fprintf(stderr, "Unsupported codec!\n");

        return -1;

    }



    // Copy context

    aCodecCtx = avcodec_alloc_context3(aCodec);

    if (avcodec_copy_context(aCodecCtx, aCodecCtxOrig) != 0) {

        fprintf(stderr, "Couldn't copy codec context");

        return -1; // Error copying codec context

    }





    wanted_spec.freq = aCodecCtx->sample_rate;

    wanted_spec.format = AUDIO_U16SYS;

    wanted_spec.channels = aCodecCtx->channels;

    wanted_spec.silence = 0;

    wanted_spec.samples = SDL_AUDIO_BUFFER_SIZE;

    wanted_spec.callback = audio_callback;

    wanted_spec.userdata = aCodecCtx;





    if (SDL_OpenAudio( &amp;wanted_spec, &amp;spec) &lt; 0) {

        fprintf(stderr, "SDL_OpenAudio: %s\n", SDL_GetError());

        return -1;

    }



    avcodec_open2(aCodecCtx, aCodec, NULL);



    // audio_st = pFormatCtx->streams[index]

    packet_queue_init(&amp;audioq);

    SDL_PauseAudio(0);

The Call back (same as the tutorial) :|

void audio_callback(void *userdata, Uint8 *stream, int len) {



    AVCodecContext *aCodecCtx = (AVCodecContext *)userdata;

    int len1, audio_size;



    static uint8_t audio_buf[(MAX_AUDIO_FRAME_SIZE * 3) / 2];

    static unsigned int audio_buf_size = 0;

    static unsigned int audio_buf_index = 0;



    while (len > 0) {

        if (audio_buf_index >= audio_buf_size) {

            /* We have already sent all our data; get more */

            audio_size = audio_decode_frame(aCodecCtx, audio_buf, sizeof(audio_buf));

            if (audio_size &lt; 0) {

                /* If error, output silence */

                audio_buf_size = 1024; // arbitrary?

                memset(audio_buf, 0, audio_buf_size);

            }

            else {

                audio_buf_size = audio_size;

            }

            audio_buf_index = 0;

        }

        len1 = audio_buf_size - audio_buf_index;

        if (len1 > len)

            len1 = len;

        memcpy(stream, (uint8_t *)audio_buf + audio_buf_index, len1);

        len -= len1;

        stream += len1;

        audio_buf_index += len1;

    }

}

SDL Audio - Plays only Static Noise

30 avril 2016, par bcpermafrost

Im having an issue with playing audio.

Im new to the SDL World of things so im learning from a tutorial.

http://dranger.com/ffmpeg/tutorial03.html

Here is my main loop for parsing the packets :

 while (av_read_frame(pFormatCtx, &amp;packet) >= 0) {



         if (packet.stream_index == videoStream) {

             avcodec_decode_video2(pCodecCtx, pFrame, &amp;frameFinished, &amp;packet);



             if (frameFinished){



                 AVPicture pict;



                 pict.data[0] = yPlane;

                 pict.data[1] = uPlane;

                 pict.data[2] = vPlane;

                 pict.linesize[0] = pCodecCtx->width;

                 pict.linesize[1] = uvPitch;

                 pict.linesize[2] = uvPitch;



                 sws_scale(sws_ctx,

                     pFrame->data, pFrame->linesize,

                     0, pCodecCtx->height,

                     pict.data, pict.linesize);



                 //SDL_UnlockTexture(bmp);



                 SDL_UpdateYUVTexture(bmp, 0, 

                     yPlane, pCodecCtx->width, 

                     uPlane, uvPitch, 

                     vPlane, uvPitch);





                 SDL_RenderClear(renderer);

                 SDL_RenderCopy(renderer, bmp, NULL, NULL);

                 SDL_RenderPresent(renderer);





                 av_free_packet(&amp;packet);





             }



         }

         else if (packet.stream_index == audioStream) { 

             packet_queue_put(&amp;audioq, &amp;packet);



         }

         else

             av_free_packet(&amp;packet);







         SDL_PollEvent(&amp;event);



         switch (event.type) {

         case SDL_QUIT:

             quit = 1;

             SDL_DestroyTexture(bmp);

             SDL_DestroyRenderer(renderer);

             SDL_DestroyWindow(screen);

             SDL_Quit();

             exit(0);

             break;

         default:

             break;



         }



     }

this is my initialization of the audio device :

aCodecCtxOrig = pFormatCtx->streams[audioStream]->codec;

    aCodec = avcodec_find_decoder(aCodecCtxOrig->codec_id);

    if (!aCodec) {

        fprintf(stderr, "Unsupported codec!\n");

        return -1;

    }



    // Copy context

    aCodecCtx = avcodec_alloc_context3(aCodec);

    if (avcodec_copy_context(aCodecCtx, aCodecCtxOrig) != 0) {

        fprintf(stderr, "Couldn't copy codec context");

        return -1; // Error copying codec context

    }





    wanted_spec.freq = aCodecCtx->sample_rate;

    wanted_spec.format = AUDIO_U16SYS;

    wanted_spec.channels = aCodecCtx->channels;

    wanted_spec.silence = 0;

    wanted_spec.samples = SDL_AUDIO_BUFFER_SIZE;

    wanted_spec.callback = audio_callback;

    wanted_spec.userdata = aCodecCtx;





    if (SDL_OpenAudio( &amp;wanted_spec, &amp;spec) &lt; 0) {

        fprintf(stderr, "SDL_OpenAudio: %s\n", SDL_GetError());

        return -1;

    }



    avcodec_open2(aCodecCtx, aCodec, NULL);



    // audio_st = pFormatCtx->streams[index]

    packet_queue_init(&amp;audioq);

    SDL_PauseAudio(0);

The Call back (same as the tutorial) :|

void audio_callback(void *userdata, Uint8 *stream, int len) {



    AVCodecContext *aCodecCtx = (AVCodecContext *)userdata;

    int len1, audio_size;



    static uint8_t audio_buf[(MAX_AUDIO_FRAME_SIZE * 3) / 2];

    static unsigned int audio_buf_size = 0;

    static unsigned int audio_buf_index = 0;



    while (len > 0) {

        if (audio_buf_index >= audio_buf_size) {

            /* We have already sent all our data; get more */

            audio_size = audio_decode_frame(aCodecCtx, audio_buf, sizeof(audio_buf));

            if (audio_size &lt; 0) {

                /* If error, output silence */

                audio_buf_size = 1024; // arbitrary?

                memset(audio_buf, 0, audio_buf_size);

            }

            else {

                audio_buf_size = audio_size;

            }

            audio_buf_index = 0;

        }

        len1 = audio_buf_size - audio_buf_index;

        if (len1 > len)

            len1 = len;

        memcpy(stream, (uint8_t *)audio_buf + audio_buf_index, len1);

        len -= len1;

        stream += len1;

        audio_buf_index += len1;

    }

}

1 | ... | 2048 | 2049 | 2050 | 2051 | 2052 | 2053 | 2054 | 2055 | 2056 | ... | 3503

Recherche avancée

Médias (1)

Revolution of Open-source and film making towards open film making

Autres articles (112)

Personnaliser en ajoutant son logo, sa bannière ou son image de fond

Websites made with MediaSPIP

Creating farms of unique websites

Sur d’autres sites (10509)

lavu/tx : implement aarch64 NEON SIMD FFT

SDL Audio - Plays only Static Noise

SDL Audio - Plays only Static Noise

Se connecter

Navigation

Syndication

Boussole SPIP

Recherche avancée

Médias (1)

Revolution of Open-source and film making towards open film making

Autres articles (112)

Personnaliser en ajoutant son logo, sa bannière ou son image de fond

Websites made ​​with MediaSPIP

Creating farms of unique websites

Sur d’autres sites (10509)

lavu/tx : implement aarch64 NEON SIMD FFT

SDL Audio - Plays only Static Noise

SDL Audio - Plays only Static Noise

Se connecter

Navigation

Syndication

Boussole SPIP

Websites made with MediaSPIP