root/drivers/media/platform/coda/coda-mpeg2.c

DEFINITIONS

1. coda_mpeg2_profile
2. coda_mpeg2_level
3. coda_mpeg2_parse_headers

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Coda multi-standard codec IP - MPEG-2 helper functions
   4  *
   5  * Copyright (C) 2019 Pengutronix, Philipp Zabel
   6  */
   7 
   8 #include <linux/kernel.h>
   9 #include <linux/videodev2.h>
  10 #include "coda.h"
  11 
  12 int coda_mpeg2_profile(int profile_idc)
  13 {
  14         switch (profile_idc) {
  15         case 5:
  16                 return V4L2_MPEG_VIDEO_MPEG2_PROFILE_SIMPLE;
  17         case 4:
  18                 return V4L2_MPEG_VIDEO_MPEG2_PROFILE_MAIN;
  19         case 3:
  20                 return V4L2_MPEG_VIDEO_MPEG2_PROFILE_SNR_SCALABLE;
  21         case 2:
  22                 return V4L2_MPEG_VIDEO_MPEG2_PROFILE_SPATIALLY_SCALABLE;
  23         case 1:
  24                 return V4L2_MPEG_VIDEO_MPEG2_PROFILE_HIGH;
  25         default:
  26                 return -EINVAL;
  27         }
  28 }
  29 
  30 int coda_mpeg2_level(int level_idc)
  31 {
  32         switch (level_idc) {
  33         case 10:
  34                 return V4L2_MPEG_VIDEO_MPEG2_LEVEL_LOW;
  35         case 8:
  36                 return V4L2_MPEG_VIDEO_MPEG2_LEVEL_MAIN;
  37         case 6:
  38                 return V4L2_MPEG_VIDEO_MPEG2_LEVEL_HIGH_1440;
  39         case 4:
  40                 return V4L2_MPEG_VIDEO_MPEG2_LEVEL_HIGH;
  41         default:
  42                 return -EINVAL;
  43         }
  44 }
  45 
  46 /*
  47  * Check if the buffer starts with the MPEG-2 sequence header (with or without
  48  * quantization matrix) and extension header, for example:
  49  *
  50  *   00 00 01 b3 2d 01 e0 34 08 8b a3 81
  51  *               10 11 11 12 12 12 13 13 13 13 14 14 14 14 14 15
  52  *               15 15 15 15 15 16 16 16 16 16 16 16 17 17 17 17
  53  *               17 17 17 17 18 18 18 19 18 18 18 19 1a 1a 1a 1a
  54  *               19 1b 1b 1b 1b 1b 1c 1c 1c 1c 1e 1e 1e 1f 1f 21
  55  *   00 00 01 b5 14 8a 00 01 00 00
  56  *
  57  * or:
  58  *
  59  *   00 00 01 b3 08 00 40 15 ff ff e0 28
  60  *   00 00 01 b5 14 8a 00 01 00 00
  61  *
  62  * Returns the detected header size in bytes or 0.
  63  */
  64 u32 coda_mpeg2_parse_headers(struct coda_ctx *ctx, u8 *buf, u32 size)
  65 {
  66         static const u8 sequence_header_start[4] = { 0x00, 0x00, 0x01, 0xb3 };
  67         static const union {
  68                 u8 extension_start[4];
  69                 u8 start_code_prefix[3];
  70         } u = { { 0x00, 0x00, 0x01, 0xb5 } };
  71 
  72         if (size < 22 ||
  73             memcmp(buf, sequence_header_start, 4) != 0)
  74                 return 0;
  75 
  76         if ((size == 22 ||
  77              (size >= 25 && memcmp(buf + 22, u.start_code_prefix, 3) == 0)) &&
  78             memcmp(buf + 12, u.extension_start, 4) == 0)
  79                 return 22;
  80 
  81         if ((size == 86 ||
  82              (size > 89 && memcmp(buf + 86, u.start_code_prefix, 3) == 0)) &&
  83             memcmp(buf + 76, u.extension_start, 4) == 0)
  84                 return 86;
  85 
  86         return 0;
  87 }