[FFmpeg-devel] [PATCH v2 3/3] avcodec/avs2_parser: parse more info

[Zhao Zhili]

Including video resolution, framerate and picture type, etc.

Signed-off-by: Zhao Zhili <quinkblack at foxmail.com>
---
v2: fix unused variable warning

 libavcodec/avs2.h        |  27 ++++++++++
 libavcodec/avs2_parser.c | 103 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 130 insertions(+)

diff --git a/libavcodec/avs2.h b/libavcodec/avs2.h
index f342ba52a0..e961c7d517 100644
--- a/libavcodec/avs2.h
+++ b/libavcodec/avs2.h
@@ -23,6 +23,8 @@
 #ifndef AVCODEC_AVS2_H
 #define AVCODEC_AVS2_H
 
+#include "libavutil/rational.h"
+
 #define AVS2_SLICE_MAX_START_CODE    0x000001AF
 
 enum {
@@ -38,4 +40,29 @@ enum {
 #define AVS2_ISPIC(x)  ((x) == AVS2_INTRA_PIC_START_CODE || (x) == AVS2_INTER_PIC_START_CODE)
 #define AVS2_ISUNIT(x) ((x) == AVS2_SEQ_START_CODE || AVS2_ISPIC(x))
 
+enum AVS2Profile {
+    AVS2_PROFILE_MAIN_PIC   = 0x12,
+    AVS2_PROFILE_MAIN       = 0x20,
+    AVS2_PROFILE_MAIN10     = 0x22,
+};
+
+static const AVRational ff_avs2_frame_rate_tab[16] = {
+    { 0    , 0   }, // forbid
+    { 24000, 1001},
+    { 24   , 1   },
+    { 25   , 1   },
+    { 30000, 1001},
+    { 30   , 1   },
+    { 50   , 1   },
+    { 60000, 1001},
+    { 60   , 1   },
+    { 100  , 1   },
+    { 120  , 1   },
+    { 200  , 1   },
+    { 240  , 1   },
+    { 300  , 1   },
+    { 0    , 0   }, // reserved
+    { 0    , 0   }  // reserved
+};
+
 #endif
diff --git a/libavcodec/avs2_parser.c b/libavcodec/avs2_parser.c
index 71cf442903..18d7729768 100644
--- a/libavcodec/avs2_parser.c
+++ b/libavcodec/avs2_parser.c
@@ -19,7 +19,9 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#include "libavutil/avutil.h"
 #include "avs2.h"
+#include "get_bits.h"
 #include "parser.h"
 
 static int avs2_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
@@ -58,6 +60,105 @@ static int avs2_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_siz
     return END_NOT_FOUND;
 }
 
+static void parse_avs2_seq_header(AVCodecParserContext *s, const uint8_t *buf,
+                                 int buf_size, AVCodecContext *avctx)
+{
+    GetBitContext gb;
+    int profile, level;
+    int width, height;
+    int chroma, sample_precision, encoding_precision = 1;
+    // sample_precision and encoding_precision is 3 bits
+    static uint8_t precision[8] = { 0, 8, 10 };
+    unsigned aspect_ratio;
+    unsigned frame_rate_code;
+    int low_delay;
+
+    if (buf_size < 15)
+        return;
+
+    init_get_bits8(&gb, buf, buf_size);
+
+    s->key_frame = 1;
+    s->pict_type = AV_PICTURE_TYPE_I;
+
+    profile = get_bits(&gb, 8);
+    level = get_bits(&gb, 8);
+
+    // progressive_sequence     u(1)
+    // field_coded_sequence     u(1)
+    skip_bits(&gb, 2);
+
+    width = get_bits(&gb, 14);
+    height = get_bits(&gb, 14);
+
+    chroma = get_bits(&gb, 2);
+    sample_precision = get_bits(&gb, 3);
+    if (profile == AVS2_PROFILE_MAIN10)
+        encoding_precision = get_bits(&gb, 3);
+
+    aspect_ratio = get_bits(&gb, 4);
+    frame_rate_code = get_bits(&gb, 4);
+
+    // bit_rate_lower       u(18)
+    // marker_bit           f(1)
+    // bit_rate_upper       u(12)
+    skip_bits(&gb, 31);
+
+    low_delay = get_bits(&gb, 1);
+
+    s->width = width;
+    s->height = height;
+    s->coded_width = FFALIGN(width, 8);
+    s->coded_height = FFALIGN(height, 8);
+    avctx->framerate.num = avctx->time_base.den =
+        ff_avs2_frame_rate_tab[frame_rate_code].num;
+    avctx->framerate.den = avctx->time_base.num =
+        ff_avs2_frame_rate_tab[frame_rate_code].den;
+    avctx->has_b_frames = FFMAX(avctx->has_b_frames, !low_delay);
+
+    av_log(avctx, AV_LOG_DEBUG,
+           "AVS2 parse seq HDR: profile %x, level %x, "
+           "width %d, height %d, "
+           "chroma %d, sample_precision %d bits, encoding_precision %d bits, "
+           "aspect_ratio 0x%x, framerate %d/%d, low_delay %d\n",
+           profile, level,
+           width, height,
+           chroma, precision[sample_precision], precision[encoding_precision],
+           aspect_ratio, avctx->framerate.num, avctx->framerate.den, low_delay);
+}
+
+static void parse_avs2_units(AVCodecParserContext *s, const uint8_t *buf,
+                             int buf_size, AVCodecContext *avctx)
+{
+    if (buf_size < 5)
+        return;
+
+    if (!(buf[0] == 0x0 && buf[1] == 0x0 && buf[2] == 0x1))
+        return;
+
+    switch (buf[3]) {
+    case AVS2_SEQ_START_CODE:
+        parse_avs2_seq_header(s, buf + 4, buf_size - 4, avctx);
+        return;
+    case AVS2_INTRA_PIC_START_CODE:
+        s->key_frame = 1;
+        s->pict_type = AV_PICTURE_TYPE_I;
+        return;
+    case AVS2_INTER_PIC_START_CODE:
+        s->key_frame = 0;
+        if (buf_size > 9) {
+            int pic_code_type = buf[8] & 0x3;
+            if (pic_code_type == 1)
+                s->pict_type = AV_PICTURE_TYPE_P;
+            else if (pic_code_type == 3)
+                s->pict_type = AV_PICTURE_TYPE_S;
+            else
+                s->pict_type = AV_PICTURE_TYPE_B;
+        }
+        return;
+    }
+}
+
 static int avs2_parse(AVCodecParserContext *s, AVCodecContext *avctx,
                       const uint8_t **poutbuf, int *poutbuf_size,
                       const uint8_t *buf, int buf_size)
@@ -76,6 +177,8 @@ static int avs2_parse(AVCodecParserContext *s, AVCodecContext *avctx,
         }
     }
 
+    parse_avs2_units(s, buf, buf_size, avctx);
+
     *poutbuf = buf;
     *poutbuf_size = buf_size;
 
-- 
2.35.3