mirror of
https://github.com/FFmpeg/FFmpeg.git
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d7a75d2163
It is small (16 B) and therefore the overhead of exporting it more than outweighs the size savings from not having duplicated symbols: When the symbol is no longer avpriv, one saves twice the size of the string containing the symbols name (2x30 byte), two entries in .dynsym (24 bytes each on x64), one entry in the importing libraries .got and .rela.dyn (8 + 24 bytes on x64) and two entries for the symbol version (2 bytes each) and one hash value in the exporting library (4 bytes). (The exact numbers are of course different for other platforms (e.g. when using dlls), but given that the strings saved alone more than outweigh the array size it can be presumed that this is beneficial for all platforms.) Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
392 lines
11 KiB
C
392 lines
11 KiB
C
/*
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* Apple HTTP Live Streaming Sample Encryption/Decryption
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*
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* Copyright (c) 2021 Nachiket Tarate
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* Apple HTTP Live Streaming Sample Encryption
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* https://developer.apple.com/library/ios/documentation/AudioVideo/Conceptual/HLS_Sample_Encryption
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*/
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#include "libavutil/channel_layout.h"
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#include "hls_sample_encryption.h"
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#include "libavcodec/adts_header.h"
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#include "libavcodec/adts_parser.h"
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#include "libavcodec/ac3_parser_internal.h"
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typedef struct NALUnit {
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uint8_t *data;
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int type;
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int length;
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int start_code_length;
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} NALUnit;
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typedef struct AudioFrame {
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uint8_t *data;
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int length;
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int header_length;
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} AudioFrame;
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typedef struct CodecParserContext {
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const uint8_t *buf_ptr;
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const uint8_t *buf_end;
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} CodecParserContext;
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static const int eac3_sample_rate_tab[] = { 48000, 44100, 32000, 0 };
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void ff_hls_senc_read_audio_setup_info(HLSAudioSetupInfo *info, const uint8_t *buf, size_t size)
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{
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if (size < 8)
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return;
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info->codec_tag = AV_RL32(buf);
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if (info->codec_tag == MKTAG('z','a','a','c'))
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info->codec_id = AV_CODEC_ID_AAC;
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else if (info->codec_tag == MKTAG('z','a','c','3'))
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info->codec_id = AV_CODEC_ID_AC3;
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else if (info->codec_tag == MKTAG('z','e','c','3'))
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info->codec_id = AV_CODEC_ID_EAC3;
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else
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info->codec_id = AV_CODEC_ID_NONE;
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buf += 4;
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info->priming = AV_RL16(buf);
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buf += 2;
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info->version = *buf++;
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info->setup_data_length = *buf++;
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if (info->setup_data_length > size - 8)
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info->setup_data_length = size - 8;
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if (info->setup_data_length > HLS_MAX_AUDIO_SETUP_DATA_LEN)
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return;
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memcpy(info->setup_data, buf, info->setup_data_length);
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}
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int ff_hls_senc_parse_audio_setup_info(AVStream *st, HLSAudioSetupInfo *info)
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{
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int ret = 0;
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st->codecpar->codec_tag = info->codec_tag;
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if (st->codecpar->codec_id == AV_CODEC_ID_AAC)
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return 0;
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if (st->codecpar->codec_id != AV_CODEC_ID_AC3 && st->codecpar->codec_id != AV_CODEC_ID_EAC3)
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return AVERROR_INVALIDDATA;
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if (st->codecpar->codec_id == AV_CODEC_ID_AC3) {
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AC3HeaderInfo *ac3hdr = NULL;
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ret = avpriv_ac3_parse_header(&ac3hdr, info->setup_data, info->setup_data_length);
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if (ret < 0) {
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if (ret != AVERROR(ENOMEM))
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av_free(ac3hdr);
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return ret;
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}
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st->codecpar->sample_rate = ac3hdr->sample_rate;
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st->codecpar->channels = ac3hdr->channels;
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st->codecpar->channel_layout = ac3hdr->channel_layout;
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st->codecpar->bit_rate = ac3hdr->bit_rate;
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av_free(ac3hdr);
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} else { /* Parse 'dec3' EC3SpecificBox */
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GetBitContext gb;
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int data_rate, fscod, acmod, lfeon;
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ret = init_get_bits8(&gb, info->setup_data, info->setup_data_length);
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if (ret < 0)
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return AVERROR_INVALIDDATA;
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data_rate = get_bits(&gb, 13);
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skip_bits(&gb, 3);
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fscod = get_bits(&gb, 2);
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skip_bits(&gb, 10);
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acmod = get_bits(&gb, 3);
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lfeon = get_bits(&gb, 1);
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st->codecpar->sample_rate = eac3_sample_rate_tab[fscod];
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st->codecpar->channel_layout = ff_ac3_channel_layout_tab[acmod];
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if (lfeon)
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st->codecpar->channel_layout |= AV_CH_LOW_FREQUENCY;
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st->codecpar->channels = av_get_channel_layout_nb_channels(st->codecpar->channel_layout);
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st->codecpar->bit_rate = data_rate*1000;
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}
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return 0;
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}
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/*
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* Remove start code emulation prevention 0x03 bytes
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*/
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static void remove_scep_3_bytes(NALUnit *nalu)
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{
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int i = 0;
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int j = 0;
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uint8_t *data = nalu->data;
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while (i < nalu->length) {
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if (nalu->length - i > 3 && AV_RB24(&data[i]) == 0x000003) {
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data[j++] = data[i++];
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data[j++] = data[i++];
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i++;
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} else {
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data[j++] = data[i++];
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}
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}
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nalu->length = j;
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}
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static int get_next_nal_unit(CodecParserContext *ctx, NALUnit *nalu)
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{
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const uint8_t *nalu_start = ctx->buf_ptr;
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if (ctx->buf_end - ctx->buf_ptr >= 4 && AV_RB32(ctx->buf_ptr) == 0x00000001)
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nalu->start_code_length = 4;
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else if (ctx->buf_end - ctx->buf_ptr >= 3 && AV_RB24(ctx->buf_ptr) == 0x000001)
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nalu->start_code_length = 3;
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else /* No start code at the beginning of the NAL unit */
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return -1;
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ctx->buf_ptr += nalu->start_code_length;
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while (ctx->buf_ptr < ctx->buf_end) {
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if (ctx->buf_end - ctx->buf_ptr >= 4 && AV_RB32(ctx->buf_ptr) == 0x00000001)
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break;
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else if (ctx->buf_end - ctx->buf_ptr >= 3 && AV_RB24(ctx->buf_ptr) == 0x000001)
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break;
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ctx->buf_ptr++;
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}
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nalu->data = (uint8_t *)nalu_start + nalu->start_code_length;
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nalu->length = ctx->buf_ptr - nalu->data;
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nalu->type = *nalu->data & 0x1F;
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return 0;
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}
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static int decrypt_nal_unit(HLSCryptoContext *crypto_ctx, NALUnit *nalu)
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{
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int ret = 0;
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int rem_bytes;
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uint8_t *data;
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uint8_t iv[16];
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ret = av_aes_init(crypto_ctx->aes_ctx, crypto_ctx->key, 16 * 8, 1);
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if (ret < 0)
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return ret;
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/* Remove start code emulation prevention 0x03 bytes */
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remove_scep_3_bytes(nalu);
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data = nalu->data + 32;
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rem_bytes = nalu->length - 32;
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memcpy(iv, crypto_ctx->iv, 16);
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while (rem_bytes > 0) {
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if (rem_bytes > 16) {
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av_aes_crypt(crypto_ctx->aes_ctx, data, data, 1, iv, 1);
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data += 16;
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rem_bytes -= 16;
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}
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data += FFMIN(144, rem_bytes);
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rem_bytes -= FFMIN(144, rem_bytes);
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}
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return 0;
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}
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static int decrypt_video_frame(HLSCryptoContext *crypto_ctx, AVPacket *pkt)
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{
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int ret = 0;
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CodecParserContext ctx;
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NALUnit nalu;
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uint8_t *data_ptr;
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int move_nalu = 0;
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memset(&ctx, 0, sizeof(ctx));
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ctx.buf_ptr = pkt->data;
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ctx.buf_end = pkt->data + pkt->size;
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data_ptr = pkt->data;
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while (ctx.buf_ptr < ctx.buf_end) {
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memset(&nalu, 0, sizeof(nalu));
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ret = get_next_nal_unit(&ctx, &nalu);
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if (ret < 0)
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return ret;
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if ((nalu.type == 0x01 || nalu.type == 0x05) && nalu.length > 48) {
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int encrypted_nalu_length = nalu.length;
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ret = decrypt_nal_unit(crypto_ctx, &nalu);
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if (ret < 0)
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return ret;
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move_nalu = nalu.length != encrypted_nalu_length;
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}
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if (move_nalu)
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memmove(data_ptr, nalu.data - nalu.start_code_length, nalu.start_code_length + nalu.length);
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data_ptr += nalu.start_code_length + nalu.length;
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}
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av_shrink_packet(pkt, data_ptr - pkt->data);
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return 0;
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}
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static int get_next_adts_frame(CodecParserContext *ctx, AudioFrame *frame)
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{
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int ret = 0;
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AACADTSHeaderInfo *adts_hdr = NULL;
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/* Find next sync word 0xFFF */
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while (ctx->buf_ptr < ctx->buf_end - 1) {
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if (*ctx->buf_ptr == 0xFF && (*(ctx->buf_ptr + 1) & 0xF0) == 0xF0)
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break;
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ctx->buf_ptr++;
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}
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if (ctx->buf_ptr >= ctx->buf_end - 1)
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return -1;
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frame->data = (uint8_t*)ctx->buf_ptr;
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ret = avpriv_adts_header_parse (&adts_hdr, frame->data, ctx->buf_end - frame->data);
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if (ret < 0)
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return ret;
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frame->header_length = adts_hdr->crc_absent ? AV_AAC_ADTS_HEADER_SIZE : AV_AAC_ADTS_HEADER_SIZE + 2;
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frame->length = adts_hdr->frame_length;
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av_free(adts_hdr);
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return 0;
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}
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static int get_next_ac3_eac3_sync_frame(CodecParserContext *ctx, AudioFrame *frame)
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{
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int ret = 0;
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AC3HeaderInfo *hdr = NULL;
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/* Find next sync word 0x0B77 */
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while (ctx->buf_ptr < ctx->buf_end - 1) {
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if (*ctx->buf_ptr == 0x0B && *(ctx->buf_ptr + 1) == 0x77)
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break;
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ctx->buf_ptr++;
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}
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if (ctx->buf_ptr >= ctx->buf_end - 1)
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return -1;
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frame->data = (uint8_t*)ctx->buf_ptr;
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frame->header_length = 0;
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ret = avpriv_ac3_parse_header(&hdr, frame->data, ctx->buf_end - frame->data);
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if (ret < 0) {
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if (ret != AVERROR(ENOMEM))
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av_free(hdr);
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return ret;
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}
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frame->length = hdr->frame_size;
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av_free(hdr);
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return 0;
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}
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static int get_next_sync_frame(enum AVCodecID codec_id, CodecParserContext *ctx, AudioFrame *frame)
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{
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if (codec_id == AV_CODEC_ID_AAC)
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return get_next_adts_frame(ctx, frame);
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else if (codec_id == AV_CODEC_ID_AC3 || codec_id == AV_CODEC_ID_EAC3)
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return get_next_ac3_eac3_sync_frame(ctx, frame);
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else
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return AVERROR_INVALIDDATA;
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}
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static int decrypt_sync_frame(enum AVCodecID codec_id, HLSCryptoContext *crypto_ctx, AudioFrame *frame)
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{
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int ret = 0;
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uint8_t *data;
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int num_of_encrypted_blocks;
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ret = av_aes_init(crypto_ctx->aes_ctx, crypto_ctx->key, 16 * 8, 1);
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if (ret < 0)
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return ret;
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data = frame->data + frame->header_length + 16;
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num_of_encrypted_blocks = (frame->length - frame->header_length - 16)/16;
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av_aes_crypt(crypto_ctx->aes_ctx, data, data, num_of_encrypted_blocks, crypto_ctx->iv, 1);
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return 0;
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}
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static int decrypt_audio_frame(enum AVCodecID codec_id, HLSCryptoContext *crypto_ctx, AVPacket *pkt)
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{
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int ret = 0;
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CodecParserContext ctx;
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AudioFrame frame;
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memset(&ctx, 0, sizeof(ctx));
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ctx.buf_ptr = pkt->data;
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ctx.buf_end = pkt->data + pkt->size;
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while (ctx.buf_ptr < ctx.buf_end) {
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memset(&frame, 0, sizeof(frame));
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ret = get_next_sync_frame(codec_id, &ctx, &frame);
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if (ret < 0)
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return ret;
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if (frame.length - frame.header_length > 31) {
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ret = decrypt_sync_frame(codec_id, crypto_ctx, &frame);
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if (ret < 0)
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return ret;
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}
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ctx.buf_ptr += frame.length;
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}
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return 0;
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}
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int ff_hls_senc_decrypt_frame(enum AVCodecID codec_id, HLSCryptoContext *crypto_ctx, AVPacket *pkt)
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{
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if (codec_id == AV_CODEC_ID_H264)
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return decrypt_video_frame(crypto_ctx, pkt);
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else if (codec_id == AV_CODEC_ID_AAC || codec_id == AV_CODEC_ID_AC3 || codec_id == AV_CODEC_ID_EAC3)
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return decrypt_audio_frame(codec_id, crypto_ctx, pkt);
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return AVERROR_INVALIDDATA;
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}
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