[FFmpeg-devel] [PATCH] avformat/hlsenc: fix CODECS Attribute hard code in hevc EXT-X-STREAM-INF

[Jack Lau]

fix ticket: 10786
parse the SPS from extradata and get profile_compatibility, tier, constraints which was been hard code before.

HEVC CODECS Attribute reference to: ISO/IEC14496-15
Signed-off-by: Jack Lau <jacklau1222 at qq.com>
---
 libavformat/hlsenc.c | 37 ++++++++++++++++++++++++++++++++++---
 1 file changed, 34 insertions(+), 3 deletions(-)

diff --git a/libavformat/hlsenc.c b/libavformat/hlsenc.c
index 6148685f40..be7a78021a 100644
--- a/libavformat/hlsenc.c
+++ b/libavformat/hlsenc.c
@@ -379,7 +379,10 @@ static void write_codec_attr(AVStream *st, VariantStream *vs)
     } else if (st->codecpar->codec_id == AV_CODEC_ID_HEVC) {
         uint8_t *data = st->codecpar->extradata;
         int profile = AV_PROFILE_UNKNOWN;
+        uint32_t profile_compatibility = AV_PROFILE_UNKNOWN; 
+        char tier = '0';
         int level = AV_LEVEL_UNKNOWN;
+        char constraints[5] = "0";
 
         if (st->codecpar->profile != AV_PROFILE_UNKNOWN)
             profile = st->codecpar->profile;
@@ -393,6 +396,8 @@ static void write_codec_attr(AVStream *st, VariantStream *vs)
                 uint8_t *rbsp_buf;
                 int remain_size = 0;
                 int rbsp_size = 0;
+                uint32_t profile_compatibility_flags = 0;
+                uint8_t high_nibble = 0;
                 /* skip start code + nalu header */
                 data += 6;
                 /* process by reference General NAL unit syntax */
@@ -406,8 +411,31 @@ static void write_codec_attr(AVStream *st, VariantStream *vs)
                 }
                 /* skip sps_video_parameter_set_id   u(4),
                  *      sps_max_sub_layers_minus1    u(3),
-                 *  and sps_temporal_id_nesting_flag u(1) */
+                 *  and sps_temporal_id_nesting_flag u(1) 
+                 * 
+                 * TIER represents the general_tier_flag, with 'L' indicating the flag is 0,
+                 * and 'H' indicating the flag is 1
+                 */
+                tier = (int)(rbsp_buf[1] & 0x20) == 0 ? 'L' : 'H';
                 profile = rbsp_buf[1] & 0x1f;
+                /* PROFILE_COMPATIBILITY is general_profile_compatibility_flags, but in reverse bit order,
+                 * in a hexadecimal representation (leading zeroes may be omitted).
+                 */
+                profile_compatibility_flags = (rbsp_buf[2] << 24) | (rbsp_buf[3] << 16) | (rbsp_buf[4] << 8) | rbsp_buf[5];
+                /* revise these bits to get the profile compatibility value */
+                for (int i = 0; i < 32; i++) {
+                    profile_compatibility = (profile_compatibility << 1) | (profile_compatibility_flags & 1);
+                    profile_compatibility_flags >>= 1;
+                }
+                /* skip 8 + 8 + 32
+                 * CONSTRAINTS is a hexadecimal representation of the general_constraint_indicator_flags. 
+                 * each byte is separated by a '.', and trailing zero bytes may be omitted.
+                 * drop the trailing zero bytes refer to ISO/IEC14496-15.
+                 */
+                high_nibble = rbsp_buf[7] >> 4;
+                snprintf(constraints, sizeof(constraints),
+                         high_nibble ? "%02x.%x" : "%02x",
+                         rbsp_buf[6], high_nibble);
                 /* skip 8 + 8 + 32 + 4 + 43 + 1 bit */
                 level = rbsp_buf[12];
                 av_freep(&rbsp_buf);
@@ -417,8 +445,11 @@ static void write_codec_attr(AVStream *st, VariantStream *vs)
         }
         if (st->codecpar->codec_tag == MKTAG('h','v','c','1') &&
             profile != AV_PROFILE_UNKNOWN &&
-            level != AV_LEVEL_UNKNOWN) {
-            snprintf(attr, sizeof(attr), "%s.%d.4.L%d.B01", av_fourcc2str(st->codecpar->codec_tag), profile, level);
+            profile_compatibility != AV_PROFILE_UNKNOWN &&
+            tier != '0' &&
+            level != AV_LEVEL_UNKNOWN &&
+            strcmp(constraints, "0") != 0) {
+            snprintf(attr, sizeof(attr), "%s.%d.%x.%c%d.%s", av_fourcc2str(st->codecpar->codec_tag), profile, profile_compatibility, tier, level, constraints);
         } else
             goto fail;
     } else if (st->codecpar->codec_id == AV_CODEC_ID_MP2) {
-- 
2.47.1