summaryrefslogtreecommitdiff
path: root/libavcodec/cbs_mpeg2.c
blob: 5e0757e8ee133eec1de25cd7dd60aa55eba95606 (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
/*
 * 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 "libavutil/avassert.h"

#include "cbs.h"
#include "cbs_internal.h"
#include "cbs_mpeg2.h"
#include "internal.h"


#define HEADER(name) do { \
        ff_cbs_trace_header(ctx, name); \
    } while (0)

#define CHECK(call) do { \
        err = (call); \
        if (err < 0) \
            return err; \
    } while (0)

#define FUNC_NAME(rw, codec, name) cbs_ ## codec ## _ ## rw ## _ ## name
#define FUNC_MPEG2(rw, name) FUNC_NAME(rw, mpeg2, name)
#define FUNC(name) FUNC_MPEG2(READWRITE, name)

#define SUBSCRIPTS(subs, ...) (subs > 0 ? ((int[subs + 1]){ subs, __VA_ARGS__ }) : NULL)

#define ui(width, name) \
        xui(width, name, current->name, 0, MAX_UINT_BITS(width), 0)
#define uir(width, name) \
        xui(width, name, current->name, 1, MAX_UINT_BITS(width), 0)
#define uis(width, name, subs, ...) \
        xui(width, name, current->name, 0, MAX_UINT_BITS(width), subs, __VA_ARGS__)
#define uirs(width, name, subs, ...) \
        xui(width, name, current->name, 1, MAX_UINT_BITS(width), subs, __VA_ARGS__)
#define sis(width, name, subs, ...) \
        xsi(width, name, current->name, subs, __VA_ARGS__)


#define READ
#define READWRITE read
#define RWContext GetBitContext

#define xui(width, name, var, range_min, range_max, subs, ...) do { \
        uint32_t value = 0; \
        CHECK(ff_cbs_read_unsigned(ctx, rw, width, #name, \
                                   SUBSCRIPTS(subs, __VA_ARGS__), \
                                   &value, range_min, range_max)); \
        var = value; \
    } while (0)

#define xsi(width, name, var, subs, ...) do { \
        int32_t value; \
        CHECK(ff_cbs_read_signed(ctx, rw, width, #name, \
                                 SUBSCRIPTS(subs, __VA_ARGS__), &value, \
                                 MIN_INT_BITS(width), \
                                 MAX_INT_BITS(width))); \
        var = value; \
    } while (0)

#define marker_bit() do { \
        av_unused uint32_t one; \
        CHECK(ff_cbs_read_unsigned(ctx, rw, 1, "marker_bit", NULL, &one, 1, 1)); \
    } while (0)

#define nextbits(width, compare, var) \
    (get_bits_left(rw) >= width && \
     (var = show_bits(rw, width)) == (compare))

#include "cbs_mpeg2_syntax_template.c"

#undef READ
#undef READWRITE
#undef RWContext
#undef xui
#undef xsi
#undef marker_bit
#undef nextbits


#define WRITE
#define READWRITE write
#define RWContext PutBitContext

#define xui(width, name, var, range_min, range_max, subs, ...) do { \
        CHECK(ff_cbs_write_unsigned(ctx, rw, width, #name, \
                                    SUBSCRIPTS(subs, __VA_ARGS__), \
                                    var, range_min, range_max)); \
    } while (0)

#define xsi(width, name, var, subs, ...) do { \
        CHECK(ff_cbs_write_signed(ctx, rw, width, #name, \
                                  SUBSCRIPTS(subs, __VA_ARGS__), var, \
                                  MIN_INT_BITS(width), \
                                  MAX_INT_BITS(width))); \
    } while (0)

#define marker_bit() do { \
        CHECK(ff_cbs_write_unsigned(ctx, rw, 1, "marker_bit", NULL, 1, 1, 1)); \
    } while (0)

#define nextbits(width, compare, var) (var)

#include "cbs_mpeg2_syntax_template.c"

#undef READ
#undef READWRITE
#undef RWContext
#undef xui
#undef xsi
#undef marker_bit
#undef nextbits


static void cbs_mpeg2_free_user_data(void *unit, uint8_t *content)
{
    MPEG2RawUserData *user = (MPEG2RawUserData*)content;
    av_buffer_unref(&user->user_data_ref);
    av_freep(&content);
}

static void cbs_mpeg2_free_slice(void *unit, uint8_t *content)
{
    MPEG2RawSlice *slice = (MPEG2RawSlice*)content;
    av_buffer_unref(&slice->header.extra_information_ref);
    av_buffer_unref(&slice->data_ref);
    av_freep(&content);
}

static int cbs_mpeg2_split_fragment(CodedBitstreamContext *ctx,
                                    CodedBitstreamFragment *frag,
                                    int header)
{
    const uint8_t *start, *end;
    uint8_t *unit_data;
    uint32_t start_code = -1, next_start_code = -1;
    size_t unit_size;
    int err, i, unit_type;

    start = avpriv_find_start_code(frag->data, frag->data + frag->data_size,
                                   &start_code);
    for (i = 0;; i++) {
        end = avpriv_find_start_code(start, frag->data + frag->data_size,
                                     &next_start_code);

        unit_type = start_code & 0xff;

        // The start and end pointers point at to the byte following the
        // start_code_identifier in the start code that they found.
        if (end == frag->data + frag->data_size) {
            // We didn't find a start code, so this is the final unit.
            unit_size = end - (start - 1);
        } else {
            // Unit runs from start to the beginning of the start code
            // pointed to by end (including any padding zeroes).
            unit_size = (end - 4) - (start - 1);
        }

        unit_data = (uint8_t *)start - 1;

        err = ff_cbs_insert_unit_data(ctx, frag, i, unit_type,
                                      unit_data, unit_size, frag->data_ref);
        if (err < 0)
            return err;

        if (end == frag->data + frag->data_size)
            break;

        start_code = next_start_code;
        start = end;
    }

    return 0;
}

static int cbs_mpeg2_read_unit(CodedBitstreamContext *ctx,
                               CodedBitstreamUnit *unit)
{
    GetBitContext gbc;
    int err;

    err = init_get_bits(&gbc, unit->data, 8 * unit->data_size);
    if (err < 0)
        return err;

    if (MPEG2_START_IS_SLICE(unit->type)) {
        MPEG2RawSlice *slice;
        int pos, len;

        err = ff_cbs_alloc_unit_content(ctx, unit, sizeof(*slice),
                                        &cbs_mpeg2_free_slice);
        if (err < 0)
            return err;
        slice = unit->content;

        err = cbs_mpeg2_read_slice_header(ctx, &gbc, &slice->header);
        if (err < 0)
            return err;

        pos = get_bits_count(&gbc);
        len = unit->data_size;

        slice->data_size = len - pos / 8;
        slice->data_ref  = av_buffer_ref(unit->data_ref);
        if (!slice->data_ref)
            return AVERROR(ENOMEM);
        slice->data = unit->data + pos / 8;

        slice->data_bit_start = pos % 8;

    } else {
        switch (unit->type) {
#define START(start_code, type, read_func, free_func) \
        case start_code: \
            { \
                type *header; \
                err = ff_cbs_alloc_unit_content(ctx, unit, \
                                                sizeof(*header), free_func); \
                if (err < 0) \
                    return err; \
                header = unit->content; \
                err = cbs_mpeg2_read_ ## read_func(ctx, &gbc, header); \
                if (err < 0) \
                    return err; \
            } \
            break;
            START(0x00, MPEG2RawPictureHeader,  picture_header,  NULL);
            START(0xb2, MPEG2RawUserData,       user_data,
                                            &cbs_mpeg2_free_user_data);
            START(0xb3, MPEG2RawSequenceHeader, sequence_header, NULL);
            START(0xb5, MPEG2RawExtensionData,  extension_data,  NULL);
            START(0xb8, MPEG2RawGroupOfPicturesHeader,
                                       group_of_pictures_header, NULL);
#undef START
        default:
            av_log(ctx->log_ctx, AV_LOG_ERROR, "Unknown start code %02"PRIx32".\n",
                   unit->type);
            return AVERROR_INVALIDDATA;
        }
    }

    return 0;
}

static int cbs_mpeg2_write_header(CodedBitstreamContext *ctx,
                                  CodedBitstreamUnit *unit,
                                  PutBitContext *pbc)
{
    int err;

    switch (unit->type) {
#define START(start_code, type, func) \
    case start_code: \
        err = cbs_mpeg2_write_ ## func(ctx, pbc, unit->content); \
        break;
        START(0x00, MPEG2RawPictureHeader,  picture_header);
        START(0xb2, MPEG2RawUserData,       user_data);
        START(0xb3, MPEG2RawSequenceHeader, sequence_header);
        START(0xb5, MPEG2RawExtensionData,  extension_data);
        START(0xb8, MPEG2RawGroupOfPicturesHeader, group_of_pictures_header);
#undef START
    default:
        av_log(ctx->log_ctx, AV_LOG_ERROR, "Write unimplemented for start "
               "code %02"PRIx32".\n", unit->type);
        return AVERROR_PATCHWELCOME;
    }

    return err;
}

static int cbs_mpeg2_write_slice(CodedBitstreamContext *ctx,
                                 CodedBitstreamUnit *unit,
                                 PutBitContext *pbc)
{
    MPEG2RawSlice *slice = unit->content;
    GetBitContext gbc;
    size_t bits_left;
    int err;

    err = cbs_mpeg2_write_slice_header(ctx, pbc, &slice->header);
    if (err < 0)
        return err;

    if (slice->data) {
        if (slice->data_size * 8 + 8 > put_bits_left(pbc))
            return AVERROR(ENOSPC);

        init_get_bits(&gbc, slice->data, slice->data_size * 8);
        skip_bits_long(&gbc, slice->data_bit_start);

        while (get_bits_left(&gbc) > 15)
            put_bits(pbc, 16, get_bits(&gbc, 16));

        bits_left = get_bits_left(&gbc);
        put_bits(pbc, bits_left, get_bits(&gbc, bits_left));

        // Align with zeroes.
        while (put_bits_count(pbc) % 8 != 0)
            put_bits(pbc, 1, 0);
    }

    return 0;
}

static int cbs_mpeg2_write_unit(CodedBitstreamContext *ctx,
                                CodedBitstreamUnit *unit)
{
    CodedBitstreamMPEG2Context *priv = ctx->priv_data;
    PutBitContext pbc;
    int err;

    if (!priv->write_buffer) {
        // Initial write buffer size is 1MB.
        priv->write_buffer_size = 1024 * 1024;

    reallocate_and_try_again:
        err = av_reallocp(&priv->write_buffer, priv->write_buffer_size);
        if (err < 0) {
            av_log(ctx->log_ctx, AV_LOG_ERROR, "Unable to allocate a "
                   "sufficiently large write buffer (last attempt "
                   "%"SIZE_SPECIFIER" bytes).\n", priv->write_buffer_size);
            return err;
        }
    }

    init_put_bits(&pbc, priv->write_buffer, priv->write_buffer_size);

    if (unit->type >= 0x01 && unit->type <= 0xaf)
        err = cbs_mpeg2_write_slice(ctx, unit, &pbc);
    else
        err = cbs_mpeg2_write_header(ctx, unit, &pbc);

    if (err == AVERROR(ENOSPC)) {
        // Overflow.
        priv->write_buffer_size *= 2;
        goto reallocate_and_try_again;
    }
    if (err < 0) {
        // Write failed for some other reason.
        return err;
    }

    if (put_bits_count(&pbc) % 8)
        unit->data_bit_padding = 8 - put_bits_count(&pbc) % 8;
    else
        unit->data_bit_padding = 0;

    unit->data_size = (put_bits_count(&pbc) + 7) / 8;
    flush_put_bits(&pbc);

    err = ff_cbs_alloc_unit_data(ctx, unit, unit->data_size);
    if (err < 0)
        return err;

    memcpy(unit->data, priv->write_buffer, unit->data_size);

    return 0;
}

static int cbs_mpeg2_assemble_fragment(CodedBitstreamContext *ctx,
                                       CodedBitstreamFragment *frag)
{
    uint8_t *data;
    size_t size, dp;
    int i;

    size = 0;
    for (i = 0; i < frag->nb_units; i++)
        size += 3 + frag->units[i].data_size;

    frag->data_ref = av_buffer_alloc(size + AV_INPUT_BUFFER_PADDING_SIZE);
    if (!frag->data_ref)
        return AVERROR(ENOMEM);
    data = frag->data_ref->data;

    dp = 0;
    for (i = 0; i < frag->nb_units; i++) {
        CodedBitstreamUnit *unit = &frag->units[i];

        data[dp++] = 0;
        data[dp++] = 0;
        data[dp++] = 1;

        memcpy(data + dp, unit->data, unit->data_size);
        dp += unit->data_size;
    }

    av_assert0(dp == size);

    memset(data + size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
    frag->data      = data;
    frag->data_size = size;

    return 0;
}

static void cbs_mpeg2_close(CodedBitstreamContext *ctx)
{
    CodedBitstreamMPEG2Context *priv = ctx->priv_data;

    av_freep(&priv->write_buffer);
}

const CodedBitstreamType ff_cbs_type_mpeg2 = {
    .codec_id          = AV_CODEC_ID_MPEG2VIDEO,

    .priv_data_size    = sizeof(CodedBitstreamMPEG2Context),

    .split_fragment    = &cbs_mpeg2_split_fragment,
    .read_unit         = &cbs_mpeg2_read_unit,
    .write_unit        = &cbs_mpeg2_write_unit,
    .assemble_fragment = &cbs_mpeg2_assemble_fragment,

    .close             = &cbs_mpeg2_close,
};