ffmpeg中nal type是H264_NAL_SLICE时,如何判断I/p/b帧代码
时间: 2023-07-14 22:13:31 浏览: 165
在H.264码流中,NAL(Network Abstraction Layer)单元是由多个RBSP(Raw Byte Sequence Payload)组成的,而RBSP是由多个NAL单元组成的。在NAL单元中,第一个字节的前5位表示nal_unit_type,用来标识NAL单元的类型。当nal_unit_type为H264_NAL_SLICE时,表示当前NAL单元为视频编码中的slice数据。对于每个slice数据,都可以通过解析slice header来判断当前slice的帧类型(I帧、P帧或B帧)。
I帧的slice header中包含的信息最多,P帧和B帧的slice header中则包含的信息相对较少。具体来说,可以通过查看slice_header中的first_mb_in_slice字段来判断当前slice所属的帧类型。如果first_mb_in_slice等于0,那么当前slice属于I帧;如果first_mb_in_slice不等于0且slice_type等于0,那么当前slice属于P帧;如果slice_type不等于0,那么当前slice属于B帧。
相关问题
[h264 @ 000001ef94ed8280] Format h264 detected only with low score of 1, misdetection possible! [h264 @ 000001ef94ed9f40] illegal POC type 5 [h264 @ 000001ef94ed9f40] non-existing PPS 10 referenced [AVBSFContext @ 000001ef94ee0280] Invalid NAL unit 0, skipping. Last message repeated 6 times [h264 @ 000001ef94ed9f40] Invalid NAL unit 0, skipping. Last message repeated 6 times [h264 @ 000001ef94ed9f40] slice type 32 too large at 25 [h264 @ 000001ef94ed9f40] decode_slice_header error [h264 @ 000001ef94ed9f40] no frame! [h264 @ 000001ef94ed9f40] non-existing PPS 0 referenced [AVBSFContext @ 000001ef94ee0280] Invalid NAL unit 16, skipping. Last message repeated 3 times [h264 @ 000001ef94ed9f40] Invalid NAL unit 16, skipping. Last message repeated 3 times [h264 @ 000001ef94ed9f40] data partitioning is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented. [h264 @ 000001ef94ed9f40] If you want to help, upload a sample of this file to ftp://upload.ffmpeg.org/incoming/ and contact the ffmpeg-devel mailing list. (ffmpeg-devel@ffmpeg.org) [h264 @ 000001ef94ed9f40] data partitioning is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented. [h264 @ 000001ef94ed9f40] If you want to help, upload a sample of this file to ftp://upload.ffmpeg.org/incoming/ and contact the ffmpeg-devel mailing list. (ffmpeg-devel@ffmpeg.org) [h264 @ 000001ef94ed9f40] data partitioning is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented. [h264 @ 000001ef94ed9f40] If you want to help, upload a sample of this file to ftp://upload.ffmpeg.org/incoming/ and contact the ffmpeg-devel mailing list. (ffmpeg-devel@ffmpeg.org) [h264 @ 000001ef94ed9f40] no frame! [h264 @ 000001ef94ed8280] Stream #0: not enough frames to estimate rate; consider increasing probesize [h264 @ 000001ef94ed8280] decoding for stream 0 failed [h264 @ 000001ef94ed8280] Could not find codec parameters for stream 0 (Video: h264, none): unspecified size Consider increasing the value for the 'analyzeduration' and 'probesize' options Input #0, h264, from 'C:\Users\26742\Desktop\1.264': Duration: N/A, bitrate: N/A Stream #0:0: Video: h264, none, 25 tbr, 1200k tbn, 50 tbc At least one output file must be specified
这段错误信息是由FFmpeg解码器生成的。它指出在解码H.264视频时发生了一些问题。可能的原因包括:
1. 输入文件格式不正确或损坏。
2. 编码器参数设置不正确。
3. FFmpeg版本过旧,不支持特定的H.264功能。
解决方法可能包括:
1. 检查输入文件是否正确,并尝试使用其他工具或播放器打开文件,以确认文件是否有效。
2. 更新FFmpeg到最新版本,以支持更多的H.264功能。
3. 调整FFmpeg的分析持续时间(analyzeduration)和探测大小(probesize)选项的值。
如果问题仍然存在,可以考虑将文件示例上传到FFmpeg开发者邮件列表进行咨询,以获取更多帮助和支持。
ffmepg中根据nal数据判断sps\pps\I帧、p帧、b帧
在ffmpeg中,可以使用h264_parser_parse2()函数解析NALU数据,并获取到对应的类型。具体实现可以参考以下代码示例:
```c
AVCodecParserContext *parser_ctx = av_parser_init(AV_CODEC_ID_H264);
AVPacket *pkt = av_packet_alloc();
// 假设nal数据存储在buf中
pkt->data = buf;
pkt->size = buf_size;
int ret = 0;
int nal_type = 0;
while (pkt->size > 0) {
// 解析NALU数据
ret = av_parser_parse2(parser_ctx, codec_ctx, &pkt->data, &pkt->size,
pkt->data, pkt->size, AV_NOPTS_VALUE, AV_NOPTS_VALUE, 0);
if (ret < 0) {
// 解析失败
break;
}
if (pkt->size == 0) {
// 解析完成
break;
}
nal_type = parser_ctx->nal_unit_type;
switch (nal_type) {
case H264_NAL_SPS:
// SPS帧
break;
case H264_NAL_PPS:
// PPS帧
break;
case H264_NAL_IDR_SLICE:
case H264_NAL_SLICE:
// I帧、P帧或B帧
break;
default:
// 其他类型的NALU
break;
}
}
av_packet_free(&pkt);
av_parser_close(parser_ctx);
```
其中H264_NAL_SPS、H264_NAL_PPS、H264_NAL_IDR_SLICE和H264_NAL_SLICE分别代表SPS帧、PPS帧、I帧和P/B帧。
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