From 6522ba30e93cd9060da011c8c591dce1b273c4ce Mon Sep 17 00:00:00 2001
From: Mark Thompson <sw@jkqxz.net>
Date: Tue, 18 Sep 2018 23:30:59 +0100
Subject: h264_metadata: Add option to set the level of the stream

---
 doc/bitstream_filters.texi     |  9 +++++
 libavcodec/h264_metadata_bsf.c | 90 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 99 insertions(+)

diff --git a/doc/bitstream_filters.texi b/doc/bitstream_filters.texi
index 7d7e97503a..d948c6d658 100644
--- a/doc/bitstream_filters.texi
+++ b/doc/bitstream_filters.texi
@@ -215,6 +215,15 @@ insert the string ``hello'' associated with the given UUID.
 @item delete_filler
 Deletes both filler NAL units and filler SEI messages.
 
+@item level
+Set the level in the SPS.  Refer to H.264 section A.3 and tables A-1
+to A-5.
+
+The argument must be the name of a level (for example, @samp{4.2}), a
+level_idc value (for example, @samp{42}), or the special name @samp{auto}
+indicating that the filter should attempt to guess the level from the
+input stream properties.
+
 @end table
 
 @section h264_mp4toannexb
diff --git a/libavcodec/h264_metadata_bsf.c b/libavcodec/h264_metadata_bsf.c
index 90ad4aad98..991fcfa537 100644
--- a/libavcodec/h264_metadata_bsf.c
+++ b/libavcodec/h264_metadata_bsf.c
@@ -25,6 +25,7 @@
 #include "cbs.h"
 #include "cbs_h264.h"
 #include "h264.h"
+#include "h264_levels.h"
 #include "h264_sei.h"
 
 enum {
@@ -39,6 +40,11 @@ enum {
     FLIP_VERTICAL   = 2,
 };
 
+enum {
+    LEVEL_UNSET = -2,
+    LEVEL_AUTO  = -1,
+};
+
 typedef struct H264MetadataContext {
     const AVClass *class;
 
@@ -74,6 +80,8 @@ typedef struct H264MetadataContext {
     int display_orientation;
     double rotate;
     int flip;
+
+    int level;
 } H264MetadataContext;
 
 
@@ -208,6 +216,58 @@ static int h264_metadata_update_sps(AVBSFContext *bsf,
     CROP(bottom, crop_unit_y);
 #undef CROP
 
+    if (ctx->level != LEVEL_UNSET) {
+        int level_idc;
+
+        if (ctx->level == LEVEL_AUTO) {
+            const H264LevelDescriptor *desc;
+            int64_t bit_rate;
+            int width, height;
+
+            if (sps->vui.nal_hrd_parameters_present_flag) {
+                bit_rate = (sps->vui.nal_hrd_parameters.bit_rate_value_minus1[0] + 1) *
+                     (1 << (sps->vui.nal_hrd_parameters.bit_rate_scale + 6));
+            } else if (sps->vui.vcl_hrd_parameters_present_flag) {
+                bit_rate = (sps->vui.vcl_hrd_parameters.bit_rate_value_minus1[0] + 1) *
+                     (1 << (sps->vui.vcl_hrd_parameters.bit_rate_scale + 6));
+                // Adjust for VCL vs. NAL limits.
+                bit_rate = bit_rate * 6 / 5;
+            } else {
+                bit_rate = 0;
+            }
+
+            width  = 16 * (sps->pic_width_in_mbs_minus1 + 1);
+            height = 16 * (sps->pic_height_in_map_units_minus1 + 1) *
+                (2 - sps->frame_mbs_only_flag);
+
+            desc = ff_h264_guess_level(sps->profile_idc, bit_rate,
+                                       width, height,
+                                       sps->vui.max_dec_frame_buffering);
+            if (desc) {
+                level_idc = desc->level_idc;
+            } else {
+                av_log(bsf, AV_LOG_WARNING, "Stream does not appear to "
+                       "conform to any level: using level 6.2.\n");
+                level_idc = 62;
+            }
+        } else {
+            level_idc = ctx->level;
+        }
+
+        if (level_idc == 9) {
+            if (sps->profile_idc == 66 ||
+                sps->profile_idc == 77 ||
+                sps->profile_idc == 88) {
+                sps->level_idc = 10;
+                sps->constraint_set3_flag = 1;
+            } else {
+                sps->level_idc = 9;
+            }
+        } else {
+            sps->level_idc = level_idc;
+        }
+    }
+
     if (need_vui)
         sps->vui_parameters_present_flag = 1;
 
@@ -683,6 +743,36 @@ static const AVOption h264_metadata_options[] = {
         0, AV_OPT_TYPE_CONST,
         { .i64 = FLIP_VERTICAL },   .flags = FLAGS, .unit = "flip" },
 
+    { "level", "Set level (table A-1)",
+        OFFSET(level), AV_OPT_TYPE_INT,
+        { .i64 = LEVEL_UNSET }, LEVEL_UNSET, 0xff, FLAGS, "level" },
+    { "auto", "Attempt to guess level from stream properties",
+        0, AV_OPT_TYPE_CONST,
+        { .i64 = LEVEL_AUTO }, .flags = FLAGS, .unit = "level" },
+#define LEVEL(name, value) name, NULL, 0, AV_OPT_TYPE_CONST, \
+        { .i64 = value },      .flags = FLAGS, .unit = "level"
+    { LEVEL("1",   10) },
+    { LEVEL("1b",   9) },
+    { LEVEL("1.1", 11) },
+    { LEVEL("1.2", 12) },
+    { LEVEL("1.3", 13) },
+    { LEVEL("2",   20) },
+    { LEVEL("2.1", 21) },
+    { LEVEL("2.2", 22) },
+    { LEVEL("3",   30) },
+    { LEVEL("3.1", 31) },
+    { LEVEL("3.2", 32) },
+    { LEVEL("4",   40) },
+    { LEVEL("4.1", 41) },
+    { LEVEL("4.2", 42) },
+    { LEVEL("5",   50) },
+    { LEVEL("5.1", 51) },
+    { LEVEL("5.2", 52) },
+    { LEVEL("6",   60) },
+    { LEVEL("6.1", 61) },
+    { LEVEL("6.2", 62) },
+#undef LEVEL
+
     { NULL }
 };
 
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