h264: decouple extradata parsing from the decoder

This will allow decoupling the parser from the decoder.

libavcodec/h264.c

@@ -278,117 +278,6 @@ fail:
     return AVERROR(ENOMEM); // ff_h264_free_tables will clean up for us
 }
 
-static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size,
-                            int parse_extradata);
-
-/* There are (invalid) samples in the wild with mp4-style extradata, where the
- * parameter sets are stored unescaped (i.e. as RBSP).
- * This function catches the parameter set decoding failure and tries again
- * after escaping it */
-static int decode_extradata_ps_mp4(H264Context *h, const uint8_t *buf, int buf_size)
-{
-    int ret;
-
-    ret = decode_nal_units(h, buf, buf_size, 1);
-    if (ret < 0 && !(h->avctx->err_recognition & AV_EF_EXPLODE)) {
-        GetByteContext gbc;
-        PutByteContext pbc;
-        uint8_t *escaped_buf;
-        int escaped_buf_size;
-
-        av_log(h->avctx, AV_LOG_WARNING,
-               "SPS decoding failure, trying again after escaping the NAL\n");
-
-        if (buf_size / 2 >= (INT16_MAX - AV_INPUT_BUFFER_PADDING_SIZE) / 3)
-            return AVERROR(ERANGE);
-        escaped_buf_size = buf_size * 3 / 2 + AV_INPUT_BUFFER_PADDING_SIZE;
-        escaped_buf = av_mallocz(escaped_buf_size);
-        if (!escaped_buf)
-            return AVERROR(ENOMEM);
-
-        bytestream2_init(&gbc, buf, buf_size);
-        bytestream2_init_writer(&pbc, escaped_buf, escaped_buf_size);
-
-        while (bytestream2_get_bytes_left(&gbc)) {
-            if (bytestream2_get_bytes_left(&gbc) >= 3 &&
-                bytestream2_peek_be24(&gbc) <= 3) {
-                bytestream2_put_be24(&pbc, 3);
-                bytestream2_skip(&gbc, 2);
-            } else
-                bytestream2_put_byte(&pbc, bytestream2_get_byte(&gbc));
-        }
-
-        escaped_buf_size = bytestream2_tell_p(&pbc);
-        AV_WB16(escaped_buf, escaped_buf_size - 2);
-
-        ret = decode_nal_units(h, escaped_buf, escaped_buf_size, 1);
-        av_freep(&escaped_buf);
-        if (ret < 0)
-            return ret;
-    }
-
-    return 0;
-}
-
-int ff_h264_decode_extradata(H264Context *h)
-{
-    AVCodecContext *avctx = h->avctx;
-    int ret;
-
-    if (avctx->extradata[0] == 1) {
-        int i, cnt, nalsize;
-        unsigned char *p = avctx->extradata;
-
-        h->is_avc = 1;
-
-        if (avctx->extradata_size < 7) {
-            av_log(avctx, AV_LOG_ERROR,
-                   "avcC %d too short\n", avctx->extradata_size);
-            return AVERROR_INVALIDDATA;
-        }
-        /* sps and pps in the avcC always have length coded with 2 bytes,
-         * so put a fake nal_length_size = 2 while parsing them */
-        h->nal_length_size = 2;
-        // Decode sps from avcC
-        cnt = *(p + 5) & 0x1f; // Number of sps
-        p  += 6;
-        for (i = 0; i < cnt; i++) {
-            nalsize = AV_RB16(p) + 2;
-            if (p - avctx->extradata + nalsize > avctx->extradata_size)
-                return AVERROR_INVALIDDATA;
-            ret = decode_extradata_ps_mp4(h, p, nalsize);
-            if (ret < 0) {
-                av_log(avctx, AV_LOG_ERROR,
-                       "Decoding sps %d from avcC failed\n", i);
-                return ret;
-            }
-            p += nalsize;
-        }
-        // Decode pps from avcC
-        cnt = *(p++); // Number of pps
-        for (i = 0; i < cnt; i++) {
-            nalsize = AV_RB16(p) + 2;
-            if (p - avctx->extradata + nalsize > avctx->extradata_size)
-                return AVERROR_INVALIDDATA;
-            ret = decode_extradata_ps_mp4(h, p, nalsize);
-            if (ret < 0) {
-                av_log(avctx, AV_LOG_ERROR,
-                       "Decoding pps %d from avcC failed\n", i);
-                return ret;
-            }
-            p += nalsize;
-        }
-        // Store right nal length size that will be used to parse all other nals
-        h->nal_length_size = (avctx->extradata[4] & 0x03) + 1;
-    } else {
-        h->is_avc = 0;
-        ret = decode_nal_units(h, avctx->extradata, avctx->extradata_size, 1);
-        if (ret < 0)
-            return ret;
-    }
-    return 0;
-}
-
 static int h264_init_context(AVCodecContext *avctx, H264Context *h)
 {
     int i;
@@ -462,7 +351,9 @@ av_cold int ff_h264_decode_init(AVCodecContext *avctx)
     }
 
     if (avctx->extradata_size > 0 && avctx->extradata) {
-       ret = ff_h264_decode_extradata(h);
+       ret = ff_h264_decode_extradata(avctx->extradata, avctx->extradata_size,
+                                      &h->ps, &h->is_avc, &h->nal_length_size,
+                                      avctx->err_recognition, avctx);
        if (ret < 0) {
            ff_h264_free_context(h);
            return ret;
@@ -919,8 +810,7 @@ static int get_last_needed_nal(H264Context *h)
     return nals_needed;
 }
 
-static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size,
-                            int parse_extradata)
+static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size)
 {
     AVCodecContext *const avctx = h->avctx;
     unsigned context_count = 0;
@@ -956,19 +846,6 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size,
             continue;
 
 again:
-        /* Ignore every NAL unit type except PPS and SPS during extradata
-         * parsing. Decoding slices is not possible in codec init
-         * with frame-mt */
-        if (parse_extradata && HAVE_THREADS &&
-            (h->avctx->active_thread_type & FF_THREAD_FRAME) &&
-            (nal->type != NAL_PPS && nal->type != NAL_SPS)) {
-            if (nal->type < NAL_AUD || nal->type > NAL_AUXILIARY_SLICE)
-                av_log(avctx, AV_LOG_INFO,
-                       "Ignoring NAL unit %d during extradata parsing\n",
-                       nal->type);
-            nal->type = NAL_FF_IGNORE;
-        }
-
         // FIXME these should stop being context-global variables
         h->nal_ref_idc   = nal->ref_idc;
         h->nal_unit_type = nal->type;
@@ -1183,7 +1060,7 @@ out:
         return buf_index;
     }
 
-    buf_index = decode_nal_units(h, buf, buf_size, 0);
+    buf_index = decode_nal_units(h, buf, buf_size);
     if (buf_index < 0)
         return AVERROR_INVALIDDATA;
 

libavcodec/h264.h

@@ -706,7 +706,6 @@ int ff_h264_decode_ref_pic_marking(H264Context *h, GetBitContext *gb,
 int ff_generate_sliding_window_mmcos(H264Context *h, int first_slice);
 
 void ff_h264_hl_decode_mb(const H264Context *h, H264SliceContext *sl);
-int ff_h264_decode_extradata(H264Context *h);
 int ff_h264_decode_init(AVCodecContext *avctx);
 void ff_h264_decode_init_vlc(void);
 

libavcodec/h264_parse.c

@@ -16,6 +16,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#include "bytestream.h"
 #include "get_bits.h"
 #include "golomb.h"
 #include "h264.h"
@@ -305,3 +306,146 @@ int ff_h264_init_poc(int pic_field_poc[2], int *pic_poc,
 
     return 0;
 }
+
+static int decode_extradata_ps(const uint8_t *data, int size, H264ParamSets *ps,
+                               int is_avc, void *logctx)
+{
+    H2645Packet pkt = { 0 };
+    int i, ret = 0;
+
+    ret = ff_h2645_packet_split(&pkt, data, size, logctx, is_avc, 2, AV_CODEC_ID_H264);
+    if (ret < 0)
+        goto fail;
+
+    for (i = 0; i < pkt.nb_nals; i++) {
+        H2645NAL *nal = &pkt.nals[i];
+        switch (nal->type) {
+        case NAL_SPS:
+            ret = ff_h264_decode_seq_parameter_set(&nal->gb, logctx, ps);
+            if (ret < 0)
+                goto fail;
+            break;
+        case NAL_PPS:
+            ret = ff_h264_decode_picture_parameter_set(&nal->gb, logctx, ps,
+                                                       nal->size_bits);
+            if (ret < 0)
+                goto fail;
+            break;
+        default:
+            av_log(logctx, AV_LOG_VERBOSE, "Ignoring NAL type %d in extradata\n",
+                   nal->type);
+            break;
+        }
+    }
+
+fail:
+    ff_h2645_packet_uninit(&pkt);
+    return ret;
+}
+
+/* There are (invalid) samples in the wild with mp4-style extradata, where the
+ * parameter sets are stored unescaped (i.e. as RBSP).
+ * This function catches the parameter set decoding failure and tries again
+ * after escaping it */
+static int decode_extradata_ps_mp4(const uint8_t *buf, int buf_size, H264ParamSets *ps,
+                                   int err_recognition, void *logctx)
+{
+    int ret;
+
+    ret = decode_extradata_ps(buf, buf_size, ps, 1, logctx);
+    if (ret < 0 && !(err_recognition & AV_EF_EXPLODE)) {
+        GetByteContext gbc;
+        PutByteContext pbc;
+        uint8_t *escaped_buf;
+        int escaped_buf_size;
+
+        av_log(logctx, AV_LOG_WARNING,
+               "SPS decoding failure, trying again after escaping the NAL\n");
+
+        if (buf_size / 2 >= (INT16_MAX - AV_INPUT_BUFFER_PADDING_SIZE) / 3)
+            return AVERROR(ERANGE);
+        escaped_buf_size = buf_size * 3 / 2 + AV_INPUT_BUFFER_PADDING_SIZE;
+        escaped_buf = av_mallocz(escaped_buf_size);
+        if (!escaped_buf)
+            return AVERROR(ENOMEM);
+
+        bytestream2_init(&gbc, buf, buf_size);
+        bytestream2_init_writer(&pbc, escaped_buf, escaped_buf_size);
+
+        while (bytestream2_get_bytes_left(&gbc)) {
+            if (bytestream2_get_bytes_left(&gbc) >= 3 &&
+                bytestream2_peek_be24(&gbc) <= 3) {
+                bytestream2_put_be24(&pbc, 3);
+                bytestream2_skip(&gbc, 2);
+            } else
+                bytestream2_put_byte(&pbc, bytestream2_get_byte(&gbc));
+        }
+
+        escaped_buf_size = bytestream2_tell_p(&pbc);
+        AV_WB16(escaped_buf, escaped_buf_size - 2);
+
+        ret = decode_extradata_ps(escaped_buf, escaped_buf_size, ps, 1, logctx);
+        av_freep(&escaped_buf);
+        if (ret < 0)
+            return ret;
+    }
+
+    return 0;
+}
+
+int ff_h264_decode_extradata(const uint8_t *data, int size, H264ParamSets *ps,
+                             int *is_avc, int *nal_length_size,
+                             int err_recognition, void *logctx)
+{
+    int ret;
+
+    if (data[0] == 1) {
+        int i, cnt, nalsize;
+        const uint8_t *p = data;
+
+        *is_avc = 1;
+
+        if (size < 7) {
+            av_log(logctx, AV_LOG_ERROR, "avcC %d too short\n", size);
+            return AVERROR_INVALIDDATA;
+        }
+
+        // Decode sps from avcC
+        cnt = *(p + 5) & 0x1f; // Number of sps
+        p  += 6;
+        for (i = 0; i < cnt; i++) {
+            nalsize = AV_RB16(p) + 2;
+            if (p - data + nalsize > size)
+                return AVERROR_INVALIDDATA;
+            ret = decode_extradata_ps_mp4(p, nalsize, ps, err_recognition, logctx);
+            if (ret < 0) {
+                av_log(logctx, AV_LOG_ERROR,
+                       "Decoding sps %d from avcC failed\n", i);
+                return ret;
+            }
+            p += nalsize;
+        }
+        // Decode pps from avcC
+        cnt = *(p++); // Number of pps
+        for (i = 0; i < cnt; i++) {
+            nalsize = AV_RB16(p) + 2;
+            if (p - data + nalsize > size)
+                return AVERROR_INVALIDDATA;
+            ret = decode_extradata_ps_mp4(p, nalsize, ps, err_recognition, logctx);
+            if (ret < 0) {
+                av_log(logctx, AV_LOG_ERROR,
+                       "Decoding pps %d from avcC failed\n", i);
+                return ret;
+            }
+            p += nalsize;
+        }
+        // Store right nal length size that will be used to parse all other nals
+        *nal_length_size = (data[4] & 0x03) + 1;
+    } else {
+        *is_avc = 0;
+        ret = decode_extradata_ps(data, size, ps, 0, logctx);
+        if (ret < 0)
+            return ret;
+    }
+    return 0;
+}

libavcodec/h264_parse.h

@@ -54,6 +54,7 @@ typedef struct H264POCContext {
 
 struct SPS;
 struct PPS;
+struct H264ParamSets;
 
 int ff_h264_pred_weight_table(GetBitContext *gb, const struct SPS *sps,
                               const int *ref_count, int slice_type_nos,
@@ -82,4 +83,8 @@ int ff_h264_init_poc(int pic_field_poc[2], int *pic_poc,
                      const struct SPS *sps, H264POCContext *poc,
                      int picture_structure, int nal_ref_idc);
 
+int ff_h264_decode_extradata(const uint8_t *data, int size, struct H264ParamSets *ps,
+                             int *is_avc, int *nal_length_size,
+                             int err_recognition, void *logctx);
+
 #endif /* AVCODEC_H264_PARSE_H */

libavcodec/h264_parser.c

@@ -50,6 +50,8 @@ typedef struct H264ParseContext {
     H264DSPContext h264dsp;
     H264POCContext poc;
     H264SEIContext sei;
+    int is_avc;
+    int nal_length_size;
     int got_first;
 } H264ParseContext;
 
@@ -500,7 +502,9 @@ static int h264_parse(AVCodecParserContext *s,
             // NB: estimate_timings_from_pts behaves exactly like this.
             if (!avctx->has_b_frames)
                 h->low_delay = 1;
-            ff_h264_decode_extradata(h);
+            ff_h264_decode_extradata(avctx->extradata, avctx->extradata_size,
+                                     &p->ps, &p->is_avc, &p->nal_length_size,
+                                     avctx->err_recognition, avctx);
         }
     }