avc_utils.cpp revision 5bc087c573c70c84c6a39946457590b42d392a33 
1/*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17//#define LOG_NDEBUG 0
18#define LOG_TAG "avc_utils"
19#include <utils/Log.h>
20
21#include "include/avc_utils.h"
22
23#include <media/stagefright/foundation/ABitReader.h>
24#include <media/stagefright/foundation/ADebug.h>
25#include <media/stagefright/MediaDefs.h>
26#include <media/stagefright/MediaErrors.h>
27#include <media/stagefright/MetaData.h>
28
29namespace android {
30
31unsigned parseUE(ABitReader *br) {
32    unsigned numZeroes = 0;
33    while (br->getBits(1) == 0) {
34        ++numZeroes;
35    }
36
37    unsigned x = br->getBits(numZeroes);
38
39    return x + (1u << numZeroes) - 1;
40}
41
42// Determine video dimensions from the sequence parameterset.
43void FindAVCDimensions(
44        const sp<ABuffer> &seqParamSet, int32_t *width, int32_t *height) {
45    ABitReader br(seqParamSet->data() + 1, seqParamSet->size() - 1);
46
47    unsigned profile_idc = br.getBits(8);
48    br.skipBits(16);
49    parseUE(&br);  // seq_parameter_set_id
50
51    unsigned chroma_format_idc = 1;  // 4:2:0 chroma format
52
53    if (profile_idc == 100 || profile_idc == 110
54            || profile_idc == 122 || profile_idc == 244
55            || profile_idc == 44 || profile_idc == 83 || profile_idc == 86) {
56        chroma_format_idc = parseUE(&br);
57        if (chroma_format_idc == 3) {
58            br.skipBits(1);  // residual_colour_transform_flag
59        }
60        parseUE(&br);  // bit_depth_luma_minus8
61        parseUE(&br);  // bit_depth_chroma_minus8
62        br.skipBits(1);  // qpprime_y_zero_transform_bypass_flag
63        CHECK_EQ(br.getBits(1), 0u);  // seq_scaling_matrix_present_flag
64    }
65
66    parseUE(&br);  // log2_max_frame_num_minus4
67    unsigned pic_order_cnt_type = parseUE(&br);
68
69    if (pic_order_cnt_type == 0) {
70        parseUE(&br);  // log2_max_pic_order_cnt_lsb_minus4
71    } else if (pic_order_cnt_type == 1) {
72        // offset_for_non_ref_pic, offset_for_top_to_bottom_field and
73        // offset_for_ref_frame are technically se(v), but since we are
74        // just skipping over them the midpoint does not matter.
75
76        br.getBits(1);  // delta_pic_order_always_zero_flag
77        parseUE(&br);  // offset_for_non_ref_pic
78        parseUE(&br);  // offset_for_top_to_bottom_field
79
80        unsigned num_ref_frames_in_pic_order_cnt_cycle = parseUE(&br);
81        for (unsigned i = 0; i < num_ref_frames_in_pic_order_cnt_cycle; ++i) {
82            parseUE(&br);  // offset_for_ref_frame
83        }
84    }
85
86    parseUE(&br);  // num_ref_frames
87    br.getBits(1);  // gaps_in_frame_num_value_allowed_flag
88
89    unsigned pic_width_in_mbs_minus1 = parseUE(&br);
90    unsigned pic_height_in_map_units_minus1 = parseUE(&br);
91    unsigned frame_mbs_only_flag = br.getBits(1);
92
93    *width = pic_width_in_mbs_minus1 * 16 + 16;
94
95    *height = (2 - frame_mbs_only_flag)
96        * (pic_height_in_map_units_minus1 * 16 + 16);
97
98    if (!frame_mbs_only_flag) {
99        br.getBits(1);  // mb_adaptive_frame_field_flag
100    }
101
102    br.getBits(1);  // direct_8x8_inference_flag
103
104    if (br.getBits(1)) {  // frame_cropping_flag
105        unsigned frame_crop_left_offset = parseUE(&br);
106        unsigned frame_crop_right_offset = parseUE(&br);
107        unsigned frame_crop_top_offset = parseUE(&br);
108        unsigned frame_crop_bottom_offset = parseUE(&br);
109
110        unsigned cropUnitX, cropUnitY;
111        if (chroma_format_idc == 0  /* monochrome */) {
112            cropUnitX = 1;
113            cropUnitY = 2 - frame_mbs_only_flag;
114        } else {
115            unsigned subWidthC = (chroma_format_idc == 3) ? 1 : 2;
116            unsigned subHeightC = (chroma_format_idc == 1) ? 2 : 1;
117
118            cropUnitX = subWidthC;
119            cropUnitY = subHeightC * (2 - frame_mbs_only_flag);
120        }
121
122        LOGV("frame_crop = (%u, %u, %u, %u), cropUnitX = %u, cropUnitY = %u",
123             frame_crop_left_offset, frame_crop_right_offset,
124             frame_crop_top_offset, frame_crop_bottom_offset,
125             cropUnitX, cropUnitY);
126
127        *width -=
128            (frame_crop_left_offset + frame_crop_right_offset) * cropUnitX;
129        *height -=
130            (frame_crop_top_offset + frame_crop_bottom_offset) * cropUnitY;
131    }
132}
133
134status_t getNextNALUnit(
135        const uint8_t **_data, size_t *_size,
136        const uint8_t **nalStart, size_t *nalSize,
137        bool startCodeFollows) {
138    const uint8_t *data = *_data;
139    size_t size = *_size;
140
141    *nalStart = NULL;
142    *nalSize = 0;
143
144    if (size == 0) {
145        return -EAGAIN;
146    }
147
148    // Skip any number of leading 0x00.
149
150    size_t offset = 0;
151    while (offset < size && data[offset] == 0x00) {
152        ++offset;
153    }
154
155    if (offset == size) {
156        return -EAGAIN;
157    }
158
159    // A valid startcode consists of at least two 0x00 bytes followed by 0x01.
160
161    if (offset < 2 || data[offset] != 0x01) {
162        return ERROR_MALFORMED;
163    }
164
165    ++offset;
166
167    size_t startOffset = offset;
168
169    for (;;) {
170        while (offset < size && data[offset] != 0x01) {
171            ++offset;
172        }
173
174        if (offset == size) {
175            if (startCodeFollows) {
176                offset = size + 2;
177                break;
178            }
179
180            return -EAGAIN;
181        }
182
183        if (data[offset - 1] == 0x00 && data[offset - 2] == 0x00) {
184            break;
185        }
186
187        ++offset;
188    }
189
190    size_t endOffset = offset - 2;
191    while (data[endOffset - 1] == 0x00) {
192        --endOffset;
193    }
194
195    *nalStart = &data[startOffset];
196    *nalSize = endOffset - startOffset;
197
198    if (offset + 2 < size) {
199        *_data = &data[offset - 2];
200        *_size = size - offset + 2;
201    } else {
202        *_data = NULL;
203        *_size = 0;
204    }
205
206    return OK;
207}
208
209static sp<ABuffer> FindNAL(
210        const uint8_t *data, size_t size, unsigned nalType,
211        size_t *stopOffset) {
212    const uint8_t *nalStart;
213    size_t nalSize;
214    while (getNextNALUnit(&data, &size, &nalStart, &nalSize, true) == OK) {
215        if ((nalStart[0] & 0x1f) == nalType) {
216            sp<ABuffer> buffer = new ABuffer(nalSize);
217            memcpy(buffer->data(), nalStart, nalSize);
218            return buffer;
219        }
220    }
221
222    return NULL;
223}
224
225const char *AVCProfileToString(uint8_t profile) {
226    switch (profile) {
227        case kAVCProfileBaseline:
228            return "Baseline";
229        case kAVCProfileMain:
230            return "Main";
231        case kAVCProfileExtended:
232            return "Extended";
233        case kAVCProfileHigh:
234            return "High";
235        case kAVCProfileHigh10:
236            return "High 10";
237        case kAVCProfileHigh422:
238            return "High 422";
239        case kAVCProfileHigh444:
240            return "High 444";
241        case kAVCProfileCAVLC444Intra:
242            return "CAVLC 444 Intra";
243        default:   return "Unknown";
244    }
245}
246
247sp<MetaData> MakeAVCCodecSpecificData(const sp<ABuffer> &accessUnit) {
248    const uint8_t *data = accessUnit->data();
249    size_t size = accessUnit->size();
250
251    sp<ABuffer> seqParamSet = FindNAL(data, size, 7, NULL);
252    if (seqParamSet == NULL) {
253        return NULL;
254    }
255
256    int32_t width, height;
257    FindAVCDimensions(seqParamSet, &width, &height);
258
259    size_t stopOffset;
260    sp<ABuffer> picParamSet = FindNAL(data, size, 8, &stopOffset);
261    CHECK(picParamSet != NULL);
262
263    size_t csdSize =
264        1 + 3 + 1 + 1
265        + 2 * 1 + seqParamSet->size()
266        + 1 + 2 * 1 + picParamSet->size();
267
268    sp<ABuffer> csd = new ABuffer(csdSize);
269    uint8_t *out = csd->data();
270
271    *out++ = 0x01;  // configurationVersion
272    memcpy(out, seqParamSet->data() + 1, 3);  // profile/level...
273
274    uint8_t profile = out[0];
275    uint8_t level = out[2];
276
277    out += 3;
278    *out++ = (0x3f << 2) | 1;  // lengthSize == 2 bytes
279    *out++ = 0xe0 | 1;
280
281    *out++ = seqParamSet->size() >> 8;
282    *out++ = seqParamSet->size() & 0xff;
283    memcpy(out, seqParamSet->data(), seqParamSet->size());
284    out += seqParamSet->size();
285
286    *out++ = 1;
287
288    *out++ = picParamSet->size() >> 8;
289    *out++ = picParamSet->size() & 0xff;
290    memcpy(out, picParamSet->data(), picParamSet->size());
291
292#if 0
293    LOGI("AVC seq param set");
294    hexdump(seqParamSet->data(), seqParamSet->size());
295#endif
296
297    sp<MetaData> meta = new MetaData;
298    meta->setCString(kKeyMIMEType, MEDIA_MIMETYPE_VIDEO_AVC);
299
300    meta->setData(kKeyAVCC, 0, csd->data(), csd->size());
301    meta->setInt32(kKeyWidth, width);
302    meta->setInt32(kKeyHeight, height);
303
304    LOGI("found AVC codec config (%d x %d, %s-profile level %d.%d)",
305         width, height, AVCProfileToString(profile), level / 10, level % 10);
306
307    return meta;
308}
309
310bool IsIDR(const sp<ABuffer> &buffer) {
311    const uint8_t *data = buffer->data();
312    size_t size = buffer->size();
313
314    bool foundIDR = false;
315
316    const uint8_t *nalStart;
317    size_t nalSize;
318    while (getNextNALUnit(&data, &size, &nalStart, &nalSize, true) == OK) {
319        CHECK_GT(nalSize, 0u);
320
321        unsigned nalType = nalStart[0] & 0x1f;
322
323        if (nalType == 5) {
324            foundIDR = true;
325            break;
326        }
327    }
328
329    return foundIDR;
330}
331
332}  // namespace android
333
334