summaryrefslogtreecommitdiff
path: root/libavdevice/decklink_enc.cpp
blob: 3d7cbe237cd697479d6496e0b11f1aea51792291 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
/*
 * Blackmagic DeckLink output
 * Copyright (c) 2013-2014 Ramiro Polla
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <DeckLinkAPI.h>
#ifdef _WIN32
#include <DeckLinkAPI_i.c>
typedef unsigned long buffercount_type;
#else
#include <DeckLinkAPIDispatch.cpp>
typedef uint32_t buffercount_type;
#endif

#include <pthread.h>
#include <semaphore.h>

extern "C" {
#include "libavformat/avformat.h"
#include "libavformat/internal.h"
#include "libavutil/imgutils.h"
}

#include "decklink_enc.h"

class decklink_callback;

struct decklink_ctx {
    /* DeckLink SDK interfaces */
    IDeckLink *dl;
    IDeckLinkOutput *dlo;
    decklink_callback *callback;

    /* DeckLink mode information */
    IDeckLinkDisplayModeIterator *itermode;
    BMDTimeValue bmd_tb_den;
    BMDTimeValue bmd_tb_num;
    BMDDisplayMode bmd_mode;
    int bmd_width;
    int bmd_height;

    /* Streams present */
    int audio;
    int video;

    /* Status */
    int playback_started;
    int64_t last_pts;

    /* Options */
    int list_devices;
    int list_formats;
    double preroll;

    int frames_preroll;
    int frames_buffer;

    sem_t semaphore;

    int channels;
};

/* DeckLink callback class declaration */
class decklink_frame : public IDeckLinkVideoFrame
{
public:
    decklink_frame(struct decklink_ctx *ctx, AVFrame *avframe, long width,
                   long height, void *buffer) :
                   _ctx(ctx), _avframe(avframe), _width(width),
                   _height(height), _buffer(buffer), _refs(0) { }

    virtual long           STDMETHODCALLTYPE GetWidth      (void)          { return _width; }
    virtual long           STDMETHODCALLTYPE GetHeight     (void)          { return _height; }
    virtual long           STDMETHODCALLTYPE GetRowBytes   (void)          { return _width<<1; }
    virtual BMDPixelFormat STDMETHODCALLTYPE GetPixelFormat(void)          { return bmdFormat8BitYUV; }
    virtual BMDFrameFlags  STDMETHODCALLTYPE GetFlags      (void)          { return bmdVideoOutputFlagDefault; }
    virtual HRESULT        STDMETHODCALLTYPE GetBytes      (void **buffer) { *buffer = _buffer; return S_OK; }

    virtual HRESULT STDMETHODCALLTYPE GetTimecode     (BMDTimecodeFormat format, IDeckLinkTimecode **timecode) { return S_FALSE; }
    virtual HRESULT STDMETHODCALLTYPE GetAncillaryData(IDeckLinkVideoFrameAncillary **ancillary)               { return S_FALSE; }

    virtual HRESULT STDMETHODCALLTYPE QueryInterface(REFIID iid, LPVOID *ppv) { return E_NOINTERFACE; }
    virtual ULONG   STDMETHODCALLTYPE AddRef(void)                            { return ++_refs; }
    virtual ULONG   STDMETHODCALLTYPE Release(void)                           { if (!--_refs) delete this; return _refs; }

    struct decklink_ctx *_ctx;
    AVFrame *_avframe;

private:
    long  _width;
    long  _height;
    void *_buffer;
    int   _refs;
};

class decklink_callback : public IDeckLinkVideoOutputCallback
{
public:
    virtual HRESULT STDMETHODCALLTYPE ScheduledFrameCompleted(IDeckLinkVideoFrame *_frame, BMDOutputFrameCompletionResult result)
    {
        decklink_frame *frame = static_cast<decklink_frame *>(_frame);
        struct decklink_ctx *ctx = frame->_ctx;
        AVFrame *avframe = frame->_avframe;

        av_frame_free(&avframe);

        sem_post(&ctx->semaphore);

        return S_OK;
    }
    virtual HRESULT STDMETHODCALLTYPE ScheduledPlaybackHasStopped(void)       { return S_OK; }
    virtual HRESULT STDMETHODCALLTYPE QueryInterface(REFIID iid, LPVOID *ppv) { return E_NOINTERFACE; }
    virtual ULONG   STDMETHODCALLTYPE AddRef(void)                            { return 1; }
    virtual ULONG   STDMETHODCALLTYPE Release(void)                           { return 1; }
};

#ifdef _WIN32
static IDeckLinkIterator *CreateDeckLinkIteratorInstance(void)
{
    IDeckLinkIterator *iter;

    if (CoInitialize(NULL) != S_OK) {
        av_log(NULL, AV_LOG_ERROR, "COM initialization failed.\n");
        return NULL;
    }

    if (CoCreateInstance(CLSID_CDeckLinkIterator, NULL, CLSCTX_ALL,
                         IID_IDeckLinkIterator, (void**) &iter) != S_OK) {
        av_log(NULL, AV_LOG_ERROR, "DeckLink drivers not installed.\n");
        return NULL;
    }

    return iter;
}
#endif

/* free() is needed for a string returned by the DeckLink SDL. */
#undef free

#ifdef _WIN32
static char *dup_wchar_to_utf8(wchar_t *w)
{
    char *s = NULL;
    int l = WideCharToMultiByte(CP_UTF8, 0, w, -1, 0, 0, 0, 0);
    s = (char *) av_malloc(l);
    if (s)
        WideCharToMultiByte(CP_UTF8, 0, w, -1, s, l, 0, 0);
    return s;
}
#define DECKLINK_STR    OLECHAR *
#define DECKLINK_STRDUP dup_wchar_to_utf8
#else
#define DECKLINK_STR    const char *
#define DECKLINK_STRDUP av_strdup
#endif

static HRESULT IDeckLink_GetDisplayName(IDeckLink *This, const char **displayName)
{
    DECKLINK_STR tmpDisplayName;
    HRESULT hr = This->GetDisplayName(&tmpDisplayName);
    if (hr != S_OK)
        return hr;
    *displayName = DECKLINK_STRDUP(tmpDisplayName);
    free((void *) tmpDisplayName);
    return hr;
}

static int decklink_set_format(struct decklink_ctx *ctx,
                               int width, int height,
                               int tb_num, int tb_den)
{
    BMDDisplayModeSupport support;
    IDeckLinkDisplayMode *mode;

    if (tb_num == 1) {
        tb_num *= 1000;
        tb_den *= 1000;
    }
    ctx->bmd_mode = bmdModeUnknown;
    while ((ctx->bmd_mode == bmdModeUnknown) && ctx->itermode->Next(&mode) == S_OK) {
        BMDTimeValue bmd_tb_num, bmd_tb_den;
        int bmd_width  = mode->GetWidth();
        int bmd_height = mode->GetHeight();

        mode->GetFrameRate(&bmd_tb_num, &bmd_tb_den);

        if (bmd_width == width && bmd_height == height &&
            bmd_tb_num == tb_num && bmd_tb_den == tb_den) {
            ctx->bmd_mode   = mode->GetDisplayMode();
            ctx->bmd_width  = bmd_width;
            ctx->bmd_height = bmd_height;
            ctx->bmd_tb_den = bmd_tb_den;
            ctx->bmd_tb_num = bmd_tb_num;
        }

        mode->Release();
    }
    if (ctx->bmd_mode == bmdModeUnknown)
        return -1;
    if (ctx->dlo->DoesSupportVideoMode(ctx->bmd_mode, bmdFormat8BitYUV,
                                       bmdVideoOutputFlagDefault,
                                       &support, NULL) != S_OK)
        return -1;
    if (support == bmdDisplayModeSupported)
        return 0;

    return -1;
}

static int decklink_setup_video(AVFormatContext *avctx, AVStream *st)
{
    struct decklink_cctx *cctx = (struct decklink_cctx *) avctx->priv_data;
    struct decklink_ctx *ctx = (struct decklink_ctx *) cctx->ctx;
    AVCodecContext *c = st->codec;

    if (ctx->video) {
        av_log(avctx, AV_LOG_ERROR, "Only one video stream is supported!\n");
        return -1;
    }

    if (c->pix_fmt != AV_PIX_FMT_UYVY422) {
        av_log(avctx, AV_LOG_ERROR, "Unsupported pixel format!"
               " Only AV_PIX_FMT_UYVY422 is supported.\n");
        return -1;
    }
    if (decklink_set_format(ctx, c->width, c->height,
                            c->time_base.num, c->time_base.den)) {
        av_log(avctx, AV_LOG_ERROR, "Unsupported video size or framerate!"
               " Check available formats with -list_formats 1.\n");
        return -1;
    }
    if (ctx->dlo->EnableVideoOutput(ctx->bmd_mode,
                                    bmdVideoOutputFlagDefault) != S_OK) {
        av_log(avctx, AV_LOG_ERROR, "Could not enable video output!\n");
        return -1;
    }

    /* Set callback. */
    ctx->callback = new decklink_callback();
    ctx->dlo->SetScheduledFrameCompletionCallback(ctx->callback);

    /* Start video semaphore. */
    ctx->frames_preroll = c->time_base.den * ctx->preroll;
    if (c->time_base.den > 1000)
        ctx->frames_preroll /= 1000;

    /* Buffer twice as many frames as the preroll. */
    ctx->frames_buffer = ctx->frames_preroll * 2;
    ctx->frames_buffer = FFMIN(ctx->frames_buffer, 60);
    sem_init(&ctx->semaphore, 0, ctx->frames_buffer);

    /* The device expects the framerate to be fixed. */
    avpriv_set_pts_info(st, 64, c->time_base.num, c->time_base.den);

    ctx->video = 1;

    return 0;
}

static int decklink_setup_audio(AVFormatContext *avctx, AVStream *st)
{
    struct decklink_cctx *cctx = (struct decklink_cctx *) avctx->priv_data;
    struct decklink_ctx *ctx = (struct decklink_ctx *) cctx->ctx;
    AVCodecContext *c = st->codec;

    if (ctx->audio) {
        av_log(avctx, AV_LOG_ERROR, "Only one audio stream is supported!\n");
        return -1;
    }
    if (c->sample_rate != 48000) {
        av_log(avctx, AV_LOG_ERROR, "Unsupported sample rate!"
               " Only 48kHz is supported.\n");
        return -1;
    }
    if (c->channels != 2 && c->channels != 8) {
        av_log(avctx, AV_LOG_ERROR, "Unsupported number of channels!"
               " Only stereo and 7.1 are supported.\n");
        return -1;
    }
    if (ctx->dlo->EnableAudioOutput(bmdAudioSampleRate48kHz,
                                    bmdAudioSampleType16bitInteger,
                                    c->channels,
                                    bmdAudioOutputStreamTimestamped) != S_OK) {
        av_log(avctx, AV_LOG_ERROR, "Could not enable audio output!\n");
        return -1;
    }
    if (ctx->dlo->BeginAudioPreroll() != S_OK) {
        av_log(avctx, AV_LOG_ERROR, "Could not begin audio preroll!\n");
        return -1;
    }

    /* The device expects the sample rate to be fixed. */
    avpriv_set_pts_info(st, 64, 1, c->sample_rate);
    ctx->channels = c->channels;

    ctx->audio = 1;

    return 0;
}

av_cold int ff_decklink_write_trailer(AVFormatContext *avctx)
{
    struct decklink_cctx *cctx = (struct decklink_cctx *) avctx->priv_data;
    struct decklink_ctx *ctx = (struct decklink_ctx *) cctx->ctx;

    if (ctx->playback_started) {
        BMDTimeValue actual;
        ctx->dlo->StopScheduledPlayback(ctx->last_pts * ctx->bmd_tb_num,
                                        &actual, ctx->bmd_tb_den);
        ctx->dlo->DisableVideoOutput();
        if (ctx->audio)
            ctx->dlo->DisableAudioOutput();
    }

    if (ctx->dlo)
        ctx->dlo->Release();
    if (ctx->dl)
        ctx->dl->Release();

    if (ctx->callback)
        delete ctx->callback;

    sem_destroy(&ctx->semaphore);

    av_freep(&cctx->ctx);

    return 0;
}

static int decklink_write_video_packet(AVFormatContext *avctx, AVPacket *pkt)
{
    struct decklink_cctx *cctx = (struct decklink_cctx *) avctx->priv_data;
    struct decklink_ctx *ctx = (struct decklink_ctx *) cctx->ctx;
    AVPicture *avpicture = (AVPicture *) pkt->data;
    AVFrame *avframe, *tmp;
    decklink_frame *frame;
    buffercount_type buffered;
    HRESULT hr;

    /* HACK while av_uncoded_frame() isn't implemented */
    int ret;

    tmp = av_frame_alloc();
    if (!tmp)
        return AVERROR(ENOMEM);
    tmp->format = AV_PIX_FMT_UYVY422;
    tmp->width  = ctx->bmd_width;
    tmp->height = ctx->bmd_height;
    ret = av_frame_get_buffer(tmp, 32);
    if (ret < 0) {
        av_frame_free(&tmp);
        return ret;
    }
    av_image_copy(tmp->data, tmp->linesize, (const uint8_t **) avpicture->data,
                  avpicture->linesize, (AVPixelFormat) tmp->format, tmp->width,
                  tmp->height);
    avframe = av_frame_clone(tmp);
    av_frame_free(&tmp);
    if (!avframe) {
        av_log(avctx, AV_LOG_ERROR, "Could not clone video frame.\n");
        return AVERROR(EIO);
    }
    /* end HACK */

    frame = new decklink_frame(ctx, avframe, ctx->bmd_width, ctx->bmd_height,
                               (void *) avframe->data[0]);
    if (!frame) {
        av_log(avctx, AV_LOG_ERROR, "Could not create new frame.\n");
        return AVERROR(EIO);
    }

    /* Always keep at most one second of frames buffered. */
    sem_wait(&ctx->semaphore);

    /* Schedule frame for playback. */
    hr = ctx->dlo->ScheduleVideoFrame((struct IDeckLinkVideoFrame *) frame,
                                      pkt->pts * ctx->bmd_tb_num,
                                      ctx->bmd_tb_num, ctx->bmd_tb_den);
    if (hr != S_OK) {
        av_log(avctx, AV_LOG_ERROR, "Could not schedule video frame."
                " error %08x.\n", (uint32_t) hr);
        frame->Release();
        return AVERROR(EIO);
    }

    ctx->dlo->GetBufferedVideoFrameCount(&buffered);
    av_log(avctx, AV_LOG_DEBUG, "Buffered video frames: %d.\n", (int) buffered);
    if (pkt->pts > 2 && buffered <= 2)
        av_log(avctx, AV_LOG_WARNING, "There are not enough buffered video frames."
               " Video may misbehave!\n");

    /* Preroll video frames. */
    if (!ctx->playback_started && pkt->pts > ctx->frames_preroll) {
        av_log(avctx, AV_LOG_DEBUG, "Ending audio preroll.\n");
        if (ctx->audio && ctx->dlo->EndAudioPreroll() != S_OK) {
            av_log(avctx, AV_LOG_ERROR, "Could not end audio preroll!\n");
            return AVERROR(EIO);
        }
        av_log(avctx, AV_LOG_DEBUG, "Starting scheduled playback.\n");
        if (ctx->dlo->StartScheduledPlayback(0, ctx->bmd_tb_den, 1.0) != S_OK) {
            av_log(avctx, AV_LOG_ERROR, "Could not start scheduled playback!\n");
            return AVERROR(EIO);
        }
        ctx->playback_started = 1;
    }

    return 0;
}

static int decklink_write_audio_packet(AVFormatContext *avctx, AVPacket *pkt)
{
    struct decklink_cctx *cctx = (struct decklink_cctx *) avctx->priv_data;
    struct decklink_ctx *ctx = (struct decklink_ctx *) cctx->ctx;
    int sample_count = pkt->size / (ctx->channels << 1);
    buffercount_type buffered;

    ctx->dlo->GetBufferedAudioSampleFrameCount(&buffered);
    if (pkt->pts > 1 && !buffered)
        av_log(avctx, AV_LOG_WARNING, "There's no buffered audio."
               " Audio will misbehave!\n");

    if (ctx->dlo->ScheduleAudioSamples(pkt->data, sample_count, pkt->pts,
                                       bmdAudioSampleRate48kHz, NULL) != S_OK) {
        av_log(avctx, AV_LOG_ERROR, "Could not schedule audio samples.\n");
        return AVERROR(EIO);
    }

    return 0;
}

extern "C" {

av_cold int ff_decklink_write_header(AVFormatContext *avctx)
{
    struct decklink_cctx *cctx = (struct decklink_cctx *) avctx->priv_data;
    struct decklink_ctx *ctx;
    IDeckLinkIterator *iter;
    IDeckLink *dl = NULL;
    unsigned int n;

    ctx = (struct decklink_ctx *) av_mallocz(sizeof(struct decklink_ctx));
    if (!ctx)
        return AVERROR(ENOMEM);
    ctx->list_devices = cctx->list_devices;
    ctx->list_formats = cctx->list_formats;
    ctx->preroll      = cctx->preroll;
    cctx->ctx = ctx;

    iter = CreateDeckLinkIteratorInstance();
    if (!iter) {
        av_log(avctx, AV_LOG_ERROR, "Could not create DeckLink iterator\n");
        return AVERROR(EIO);
    }

    /* List available devices. */
    if (ctx->list_devices) {
        av_log(avctx, AV_LOG_INFO, "Blackmagic DeckLink devices:\n");
        while (iter->Next(&dl) == S_OK) {
            const char *displayName;
            IDeckLink_GetDisplayName(dl, &displayName);
            av_log(avctx, AV_LOG_INFO, "\t'%s'\n", displayName);
            av_free((void *) displayName);
            dl->Release();
        }
        iter->Release();
        return AVERROR_EXIT;
    }

    /* Open device. */
    while (iter->Next(&dl) == S_OK) {
        const char *displayName;
        IDeckLink_GetDisplayName(dl, &displayName);
        if (!strcmp(avctx->filename, displayName)) {
            av_free((void *) displayName);
            ctx->dl = dl;
            break;
        }
        av_free((void *) displayName);
        dl->Release();
    }
    iter->Release();
    if (!ctx->dl) {
        av_log(avctx, AV_LOG_ERROR, "Could not open '%s'\n", avctx->filename);
        return AVERROR(EIO);
    }

    /* Get output device. */
    if (ctx->dl->QueryInterface(IID_IDeckLinkOutput, (void **) &ctx->dlo) != S_OK) {
        av_log(avctx, AV_LOG_ERROR, "Could not open output device from '%s'\n",
               avctx->filename);
        ctx->dl->Release();
        return AVERROR(EIO);
    }

    if (ctx->dlo->GetDisplayModeIterator(&ctx->itermode) != S_OK) {
        av_log(avctx, AV_LOG_ERROR, "Could not get Display Mode Iterator\n");
        ctx->dl->Release();
        return AVERROR(EIO);
    }

    /* List supported formats. */
    if (ctx->list_formats) {
        IDeckLinkDisplayMode *mode;

        av_log(avctx, AV_LOG_INFO, "Supported formats for '%s':\n",
               avctx->filename);
        while (ctx->itermode->Next(&mode) == S_OK) {
            BMDTimeValue tb_num, tb_den;
            mode->GetFrameRate(&tb_num, &tb_den);
            av_log(avctx, AV_LOG_INFO, "\t%ldx%ld at %d/%d fps",
                   mode->GetWidth(), mode->GetHeight(),
                   (int) tb_den, (int) tb_num);
            switch (mode->GetFieldDominance()) {
            case bmdLowerFieldFirst:
            av_log(avctx, AV_LOG_INFO, " (interlaced, lower field first)"); break;
            case bmdUpperFieldFirst:
            av_log(avctx, AV_LOG_INFO, " (interlaced, upper field first)"); break;
            }
            av_log(avctx, AV_LOG_INFO, "\n");
            mode->Release();
        }

        ctx->itermode->Release();
        ctx->dlo->Release();
        ctx->dl->Release();
        return AVERROR_EXIT;
    }

    /* Setup streams. */
    for (n = 0; n < avctx->nb_streams; n++) {
        AVStream *st = avctx->streams[n];
        AVCodecContext *c = st->codec;
        if        (c->codec_type == AVMEDIA_TYPE_AUDIO) {
            if (decklink_setup_audio(avctx, st))
                goto error;
        } else if (c->codec_type == AVMEDIA_TYPE_VIDEO) {
            if (decklink_setup_video(avctx, st))
                goto error;
        } else {
            av_log(avctx, AV_LOG_ERROR, "Unsupported stream type.\n");
            goto error;
        }
    }
    ctx->itermode->Release();

    return 0;

error:

    ctx->dlo->Release();
    ctx->dl->Release();

    return AVERROR(EIO);
}

int ff_decklink_write_packet(AVFormatContext *avctx, AVPacket *pkt)
{
    struct decklink_cctx *cctx = (struct decklink_cctx *) avctx->priv_data;
    struct decklink_ctx *ctx = (struct decklink_ctx *) cctx->ctx;
    AVStream *st = avctx->streams[pkt->stream_index];

    ctx->last_pts = FFMAX(ctx->last_pts, pkt->pts);

    if      (st->codec->codec_type == AVMEDIA_TYPE_VIDEO)
        return decklink_write_video_packet(avctx, pkt);
    else if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO)
        return decklink_write_audio_packet(avctx, pkt);

    return AVERROR(EIO);
}

} /* extern "C" */